* Checks that the SDK specified with --enable-universalsk=VALUE exists.

* Fall back to the default system SDK when specifying --enable-universalsk
  without a value and the 10.4u SDK is not avaiable.

Port of fix for issue 4834 from the trunk.
diff --git a/configure b/configure
index a7f26e3..e6fcee7 100755
--- a/configure
+++ b/configure
@@ -1,5 +1,5 @@
 #! /bin/sh
-# From configure.in Revision: 77862 .
+# From configure.in Revision: 78066 .
 # Guess values for system-dependent variables and create Makefiles.
 # Generated by GNU Autoconf 2.61 for python 3.2.
 #
@@ -1886,12 +1886,18 @@
 
 CONFIG_ARGS="$ac_configure_args"
 
+{ echo "$as_me:$LINENO: checking for --enable-universalsdk" >&5
+echo $ECHO_N "checking for --enable-universalsdk... $ECHO_C" >&6; }
 # Check whether --enable-universalsdk was given.
 if test "${enable_universalsdk+set}" = set; then
   enableval=$enable_universalsdk;
 	case $enableval in
 	yes)
 		enableval=/Developer/SDKs/MacOSX10.4u.sdk
+		if test ! -d "${enableval}"
+		then
+			enableval=/
+		fi
 		;;
 	esac
 	case $enableval in
@@ -1901,9 +1907,16 @@
 		;;
 	*)
 		UNIVERSALSDK=$enableval
+		if test ! -d "${UNIVERSALSDK}"
+		then
+			{ { echo "$as_me:$LINENO: error: --enable-universalsdk specifies non-existing SDK: ${UNIVERSALSDK}" >&5
+echo "$as_me: error: --enable-universalsdk specifies non-existing SDK: ${UNIVERSALSDK}" >&2;}
+   { (exit 1); exit 1; }; }
+		fi
 		;;
 	esac
 
+
 else
 
    	UNIVERSALSDK=
@@ -1911,6 +1924,14 @@
 
 fi
 
+if test -n "${UNIVERSALSDK}"
+then
+	{ echo "$as_me:$LINENO: result: ${UNIVERSALSDK}" >&5
+echo "${ECHO_T}${UNIVERSALSDK}" >&6; }
+else
+	{ echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6; }
+fi