[2.7] Backport macOS universal build and installer fixes from 3.6. (GH-6469)

These include:

- bpo-32726: Provide an additional, more modern macOS installer variant that
  supports macOS 10.9+ systems in 64-bit mode only. Upgrade the supplied
  third-party libraries to OpenSSL 1.0.2n and SQLite 3.22.0. The 10.9+
  installer now supplies its own private copy of Tcl/Tk 8.6.8.

- bpo-24414: Default macOS deployment target is now set by ``configure`` to
  the build system's OS version (as is done by Python 3), not ``10.4``;
  override with, for example, ``./configure MACOSX_DEPLOYMENT_TARGET=10.4``.

- bpo-19019: All 2.7 macOS installer variants now supply their own version
  of ``OpenSSL 1.0.2``; the Apple-supplied SSL libraries and root
  certificates are not longer used.  The ``Installer Certificate`` command
  in ``/Applications/Python 2.7`` may be used to download and install a
  default set of root certificates from the third-party ``certifi`` package.

- bpo-11485: python.org macOS Pythons no longer supply a default SDK value
  (e.g. ``-isysroot /``) or specific compiler version default (e.g.
  ``gcc-4.2``) when building extension modules.  Use ``CC``, ``SDKROOT``,
  and ``DEVELOPER_DIR`` environment variables to override compilers or to
  use an SDK.  See Apple's ``xcrun`` man page for more info.

- prepare for pending Apple removal of 32-bit support in future macOS release
diff --git a/configure b/configure
index 3477307..4a047e6 100755
--- a/configure
+++ b/configure
@@ -1457,7 +1457,7 @@
   --disable-FEATURE       do not include FEATURE (same as --enable-FEATURE=no)
   --enable-FEATURE[=ARG]  include FEATURE [ARG=yes]
   --enable-universalsdk[=SDKDIR]
-                          Build against Mac OS X 10.4u SDK (ppc/i386)
+                          Build fat binary against Mac OS X SDK
   --enable-framework[=INSTALLDIR]
                           Build (MacOSX|Darwin) framework
   --enable-shared         disable/enable building shared python library
@@ -1477,7 +1477,8 @@
   --without-PACKAGE       do not use PACKAGE (same as --with-PACKAGE=no)
   --with-universal-archs=ARCH
                           select architectures for universal build ("32-bit",
-                          "64-bit", "3-way", "intel" or "all")
+                          "64-bit", "3-way", "intel", "intel-32", "intel-64",
+                          or "all")
   --with-framework-name=FRAMEWORK
                           specify an alternate name of the framework built
                           with --enable-framework
@@ -3039,10 +3040,16 @@
   enableval=$enable_universalsdk;
 	case $enableval in
 	yes)
-		enableval=/Developer/SDKs/MacOSX10.4u.sdk
-		if test ! -d "${enableval}"
+		# Locate the best usable SDK, see Mac/README.txt for more
+		# information
+		enableval="`/usr/bin/xcodebuild -version -sdk macosx Path 2>/dev/null`"
+		if ! ( echo $enableval | grep -E '\.sdk' 1>/dev/null )
 		then
-			enableval=/
+			enableval=/Developer/SDKs/MacOSX10.4u.sdk
+			if test ! -d "${enableval}"
+			then
+				enableval=/
+			fi
 		fi
 		;;
 	esac
@@ -3081,7 +3088,20 @@
 
 ARCH_RUN_32BIT=""
 
+# For backward compatibility reasons we prefer to select '32-bit' if available,
+# otherwise use 'intel'
 UNIVERSAL_ARCHS="32-bit"
+if test "`uname -s`" = "Darwin"
+then
+	if test -n "${UNIVERSALSDK}"
+	then
+		if test -z "`/usr/bin/file -L "${UNIVERSALSDK}/usr/lib/libSystem.dylib" | grep ppc`"
+		then
+			UNIVERSAL_ARCHS="intel"
+		fi
+	fi
+fi
+
 
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for --with-universal-archs" >&5
 $as_echo_n "checking for --with-universal-archs... " >&6; }
@@ -3089,24 +3109,18 @@
 # Check whether --with-universal-archs was given.
 if test "${with_universal_archs+set}" = set; then :
   withval=$with_universal_archs;
-	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $withval" >&5
-$as_echo "$withval" >&6; }
 	UNIVERSAL_ARCHS="$withval"
-        if test "${enable_universalsdk}" ; then
-		:
-	else
-		as_fn_error $? "--with-universal-archs without --enable-universalsdk. See Mac/README" "$LINENO" 5
-	fi
-
-else
-
- 	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: 32-bit" >&5
-$as_echo "32-bit" >&6; }
 
 fi
 
-
-
+if test -n "${UNIVERSALSDK}"
+then
+	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: ${UNIVERSAL_ARCHS}" >&5
+$as_echo "${UNIVERSAL_ARCHS}" >&6; }
+else
+	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
 
 
 # Check whether --with-framework-name was given.
@@ -6084,119 +6098,137 @@
 	SCO_SV*)
 	    BASECFLAGS="$BASECFLAGS -m486 -DSCO5"
 	    ;;
-	# is there any other compiler on Darwin besides gcc?
-	Darwin*)
-	    # -Wno-long-double, -no-cpp-precomp, and -mno-fused-madd
-	    # used to be here, but non-Apple gcc doesn't accept them.
-	    if test "${CC}" = gcc
-	    then
-		{ $as_echo "$as_me:${as_lineno-$LINENO}: checking which compiler should be used" >&5
+    # is there any other compiler on Darwin besides gcc?
+    Darwin*)
+        # -Wno-long-double, -no-cpp-precomp, and -mno-fused-madd
+        # used to be here, but non-Apple gcc doesn't accept them.
+        if test "${CC}" = gcc
+        then
+            { $as_echo "$as_me:${as_lineno-$LINENO}: checking which compiler should be used" >&5
 $as_echo_n "checking which compiler should be used... " >&6; }
-		case "${UNIVERSALSDK}" in
-		*/MacOSX10.4u.sdk)
-			# Build using 10.4 SDK, force usage of gcc when the
-			# compiler is gcc, otherwise the user will get very
-			# confusing error messages when building on OSX 10.6
-			CC=gcc-4.0
-			CPP=cpp-4.0
-			;;
-		esac
-		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $CC" >&5
+            case "${UNIVERSALSDK}" in
+            */MacOSX10.4u.sdk)
+                # Build using 10.4 SDK, force usage of gcc when the
+                # compiler is gcc, otherwise the user will get very
+                # confusing error messages when building on OSX 10.6
+                CC=gcc-4.0
+                CPP=cpp-4.0
+                ;;
+            esac
+            { $as_echo "$as_me:${as_lineno-$LINENO}: result: $CC" >&5
 $as_echo "$CC" >&6; }
-	    fi
+        fi
 
-	    # Calculate the right deployment target for this build.
-	    #
-		cur_target_major=`sw_vers -productVersion | \
-				sed 's/\([0-9]*\)\.\([0-9]*\).*/\1/'`
-		cur_target_minor=`sw_vers -productVersion | \
-				sed 's/\([0-9]*\)\.\([0-9]*\).*/\2/'`
-		cur_target="${cur_target_major}.${cur_target_minor}"
-		if test ${cur_target_major} -eq 10 && \
-		   test ${cur_target_minor} -ge 3
-		then
-		    cur_target=10.3
-		    if test ${enable_universalsdk}; then
-			    if test "${UNIVERSAL_ARCHS}" = "all"; then
-				    # Ensure that the default platform for a
-				    # 4-way universal build is OSX 10.5,
-				    # that's the first OS release where
-				    # 4-way builds make sense.
-				    cur_target='10.5'
+        if test "${enable_universalsdk}"
+        then
+            case "$UNIVERSAL_ARCHS" in
+            32-bit)
+               UNIVERSAL_ARCH_FLAGS="-arch ppc -arch i386"
+               LIPO_32BIT_FLAGS=""
+               ARCH_RUN_32BIT=""
+               ;;
+            64-bit)
+               UNIVERSAL_ARCH_FLAGS="-arch ppc64 -arch x86_64"
+               LIPO_32BIT_FLAGS=""
+               ARCH_RUN_32BIT=""
+               ;;
+            all)
+               UNIVERSAL_ARCH_FLAGS="-arch i386 -arch ppc -arch ppc64 -arch x86_64"
+               LIPO_32BIT_FLAGS="-extract ppc7400 -extract i386"
+               ARCH_RUN_32BIT="/usr/bin/arch -i386 -ppc"
+               ;;
+            intel)
+               UNIVERSAL_ARCH_FLAGS="-arch i386 -arch x86_64"
+               LIPO_32BIT_FLAGS="-extract i386"
+               ARCH_RUN_32BIT="/usr/bin/arch -i386"
+               ;;
+            intel-32)
+               UNIVERSAL_ARCH_FLAGS="-arch i386"
+               LIPO_32BIT_FLAGS=""
+               ARCH_RUN_32BIT=""
+               ;;
+            intel-64)
+               UNIVERSAL_ARCH_FLAGS="-arch x86_64"
+               LIPO_32BIT_FLAGS=""
+               ARCH_RUN_32BIT=""
+               ;;
+            3-way)
+               UNIVERSAL_ARCH_FLAGS="-arch i386 -arch ppc -arch x86_64"
+               LIPO_32BIT_FLAGS="-extract ppc7400 -extract i386"
+               ARCH_RUN_32BIT="/usr/bin/arch -i386 -ppc"
+               ;;
+            *)
+               as_fn_error $? "proper usage is --with-universal-arch=32-bit|64-bit|all|intel|3-way" "$LINENO" 5
+               ;;
+            esac
 
-			    elif test "${UNIVERSAL_ARCHS}" = "3-way"; then
-				    cur_target='10.5'
+            if test "${UNIVERSALSDK}" != "/"
+            then
+                CFLAGS="${UNIVERSAL_ARCH_FLAGS} -isysroot ${UNIVERSALSDK} ${CFLAGS}"
+                LDFLAGS="${UNIVERSAL_ARCH_FLAGS} -isysroot ${UNIVERSALSDK} ${LDFLAGS}"
+                CPPFLAGS="-isysroot ${UNIVERSALSDK} ${CPPFLAGS}"
+            else
+                CFLAGS="${UNIVERSAL_ARCH_FLAGS} ${CFLAGS}"
+                LDFLAGS="${UNIVERSAL_ARCH_FLAGS} ${LDFLAGS}"
+            fi
+        fi
 
-			    elif test "${UNIVERSAL_ARCHS}" = "intel"; then
-				    cur_target='10.5'
+        # Calculate an appropriate deployment target for this build:
+        # The deployment target value is used explicitly to enable certain
+        # features are enabled (such as builtin libedit support for readline)
+        # through the use of Apple's Availability Macros and is used as a
+        # component of the string returned by distutils.get_platform().
+        #
+        # Use the value from:
+        # 1. the MACOSX_DEPLOYMENT_TARGET environment variable if specified
+        # 2. the operating system version of the build machine if >= 10.6
+        # 3. If running on OS X 10.3 through 10.5, use the legacy tests
+        #       below to pick either 10.3, 10.4, or 10.5 as the target.
+        # 4. If we are running on OS X 10.2 or earlier, good luck!
 
-			    elif test "${UNIVERSAL_ARCHS}" = "64-bit"; then
-				    cur_target='10.5'
-			    fi
-		    else
-			    if test `/usr/bin/arch` = "i386"; then
-				    # On Intel macs default to a deployment
-				    # target of 10.4, that's the first OSX
-				    # release with Intel support.
-				    cur_target="10.4"
-			    fi
-		    fi
-	    fi
-	    CONFIGURE_MACOSX_DEPLOYMENT_TARGET=${MACOSX_DEPLOYMENT_TARGET-${cur_target}}
+        { $as_echo "$as_me:${as_lineno-$LINENO}: checking which MACOSX_DEPLOYMENT_TARGET to use" >&5
+$as_echo_n "checking which MACOSX_DEPLOYMENT_TARGET to use... " >&6; }
+        cur_target_major=`sw_vers -productVersion | \
+                sed 's/\([0-9]*\)\.\([0-9]*\).*/\1/'`
+        cur_target_minor=`sw_vers -productVersion | \
+                sed 's/\([0-9]*\)\.\([0-9]*\).*/\2/'`
+        cur_target="${cur_target_major}.${cur_target_minor}"
+        if test ${cur_target_major} -eq 10 && \
+           test ${cur_target_minor} -ge 3 && \
+           test ${cur_target_minor} -le 5
+        then
+            # OS X 10.3 through 10.5
+            cur_target=10.3
+            if test ${enable_universalsdk}
+            then
+                case "$UNIVERSAL_ARCHS" in
+                all|3-way|intel|64-bit)
+                    # These configurations were first supported in 10.5
+                    cur_target='10.5'
+                    ;;
+                esac
+            else
+                if test `/usr/bin/arch` = "i386"
+                then
+                    # 10.4 was the first release to support Intel archs
+                    cur_target="10.4"
+                fi
+            fi
+        fi
+        CONFIGURE_MACOSX_DEPLOYMENT_TARGET=${MACOSX_DEPLOYMENT_TARGET-${cur_target}}
 
-	    # Make sure that MACOSX_DEPLOYMENT_TARGET is set in the
-	    # environment with a value that is the same as what we'll use
-	    # in the Makefile to ensure that we'll get the same compiler
-	    # environment during configure and build time.
-	    MACOSX_DEPLOYMENT_TARGET="$CONFIGURE_MACOSX_DEPLOYMENT_TARGET"
-	    export MACOSX_DEPLOYMENT_TARGET
-	    EXPORT_MACOSX_DEPLOYMENT_TARGET=''
+        # Make sure that MACOSX_DEPLOYMENT_TARGET is set in the
+        # environment with a value that is the same as what we'll use
+        # in the Makefile to ensure that we'll get the same compiler
+        # environment during configure and build time.
+        MACOSX_DEPLOYMENT_TARGET="$CONFIGURE_MACOSX_DEPLOYMENT_TARGET"
+        export MACOSX_DEPLOYMENT_TARGET
+        EXPORT_MACOSX_DEPLOYMENT_TARGET=''
+        { $as_echo "$as_me:${as_lineno-$LINENO}: result: $MACOSX_DEPLOYMENT_TARGET" >&5
+$as_echo "$MACOSX_DEPLOYMENT_TARGET" >&6; }
 
-	    if test "${enable_universalsdk}"; then
-		UNIVERSAL_ARCH_FLAGS=""
-	        if test "$UNIVERSAL_ARCHS" = "32-bit" ; then
-		   UNIVERSAL_ARCH_FLAGS="-arch ppc -arch i386"
-		   ARCH_RUN_32BIT=""
-		   LIPO_32BIT_FLAGS=""
-
-	         elif test "$UNIVERSAL_ARCHS" = "64-bit" ; then
-		   UNIVERSAL_ARCH_FLAGS="-arch ppc64 -arch x86_64"
-		   LIPO_32BIT_FLAGS=""
-		   ARCH_RUN_32BIT="true"
-
-	         elif test "$UNIVERSAL_ARCHS" = "all" ; then
-		   UNIVERSAL_ARCH_FLAGS="-arch i386 -arch ppc -arch ppc64 -arch x86_64"
-		   LIPO_32BIT_FLAGS="-extract ppc7400 -extract i386"
-		   ARCH_RUN_32BIT="/usr/bin/arch -i386 -ppc"
-
-	         elif test "$UNIVERSAL_ARCHS" = "intel" ; then
-		   UNIVERSAL_ARCH_FLAGS="-arch i386 -arch x86_64"
-		   LIPO_32BIT_FLAGS="-extract i386"
-		   ARCH_RUN_32BIT="/usr/bin/arch -i386"
-
-	         elif test "$UNIVERSAL_ARCHS" = "3-way" ; then
-		   UNIVERSAL_ARCH_FLAGS="-arch i386 -arch ppc -arch x86_64"
-		   LIPO_32BIT_FLAGS="-extract ppc7400 -extract i386"
-		   ARCH_RUN_32BIT="/usr/bin/arch -i386 -ppc"
-
-		 else
-	           as_fn_error $? "proper usage is --with-universal-arch=32-bit|64-bit|all|intel|3-way" "$LINENO" 5
-
-		 fi
-
-
-		CFLAGS="${UNIVERSAL_ARCH_FLAGS} ${CFLAGS}"
-		if test "${UNIVERSALSDK}" != "/"
-		then
-			CPPFLAGS="-isysroot ${UNIVERSALSDK} ${CPPFLAGS}"
-			LDFLAGS="-isysroot ${UNIVERSALSDK} ${LDFLAGS}"
-			CFLAGS="-isysroot ${UNIVERSALSDK} ${CFLAGS}"
-		fi
-
-	    fi
-
-
-	    ;;
+        # end of Darwin* tests
+        ;;
 	OSF*)
 	    BASECFLAGS="$BASECFLAGS -mieee"
 	    ;;
@@ -6399,7 +6431,6 @@
   # compile working code using it and both test_distutils and test_gdb are
   # broken when you do managed to get a toolchain that works with it.  People
   # who want LTO need to use --with-lto themselves.
-  Py_LTO='true'
   DEF_MAKE_ALL_RULE="profile-opt"
   REQUIRE_PGO="yes"
   DEF_MAKE_RULE="build_all"
@@ -8441,7 +8472,6 @@
     		;;
     	esac
 
-	#ARCH_RUN_32BIT="true"
     fi
 
     LIBTOOL_CRUFT=$LIBTOOL_CRUFT" -lSystem -lSystemStubs -arch_only ${MACOSX_DEFAULT_ARCH}"
@@ -8618,9 +8648,6 @@
 			fi
 		else
 			# building for OS X 10.3 and later
-			if test "${enable_universalsdk}"; then
-				LDFLAGS="${UNIVERSAL_ARCH_FLAGS} -isysroot ${UNIVERSALSDK} ${LDFLAGS}"
-			fi
 			LDSHARED='$(CC) -bundle -undefined dynamic_lookup'
 			LDCXXSHARED='$(CXX) -bundle -undefined dynamic_lookup'
 			BLDSHARED="$LDSHARED"