Issue #10656: Fix out-of-tree building on AIX

The ld_so_aix script and python.exp file are created in the build directory.
Patch by Tristan Carel and Michael Haubenwallner.
diff --git a/Makefile.pre.in b/Makefile.pre.in
index f745b15..e288964 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -1232,7 +1232,7 @@
 		$(INSTALL_SCRIPT) $(srcdir)/Modules/makexp_aix	\
 				$(DESTDIR)$(LIBPL)/makexp_aix;		\
 		echo "$(LIBPL)/makexp_aix";			\
-		$(INSTALL_SCRIPT) $(srcdir)/Modules/ld_so_aix	\
+		$(INSTALL_SCRIPT) Modules/ld_so_aix	\
 				$(DESTDIR)$(LIBPL)/ld_so_aix;		\
 		echo "$(LIBPL)/ld_so_aix";			\
 		echo; echo "See Misc/AIX-NOTES for details.";	\
diff --git a/Misc/ACKS b/Misc/ACKS
index 65fd0dc..9cbc230 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -209,6 +209,7 @@
 Daniel Calvelo
 Tony Campbell
 Brett Cannon
+Tristan Carel
 Mike Carlton
 Pierre Carrier
 Terry Carroll
@@ -541,6 +542,7 @@
 Larry Hastings
 Tim Hatch
 Shane Hathaway
+Michael Haubenwallner
 Janko Hauser
 Rycharde Hawkes
 Ben Hayden
diff --git a/Misc/NEWS b/Misc/NEWS
index dbcd707..c89fe78 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -273,6 +273,9 @@
 Build
 -----
 
+- Issue #10656: Fix out-of-tree building on AIX.  Patch by Tristan Carel and
+  Michael Haubenwallner.
+
 - Issue #26359: Rename --with-optimiations to --enable-optimizations.
 
 - Issue #28248: Update Windows build and OS X installers to use OpenSSL 1.0.2j.
diff --git a/Modules/ld_so_aix.in b/Modules/ld_so_aix.in
index c18ff10..e8e98b1 100644
--- a/Modules/ld_so_aix.in
+++ b/Modules/ld_so_aix.in
@@ -70,6 +70,7 @@
 fi
 
 makexp=`dirname $0`/makexp_aix
+test -x "${makexp}" || makexp="@abs_srcdir@/makexp_aix"
 
 # Check for existence of compiler.
 CC=$1; shift
diff --git a/configure b/configure
index 4e4f9e3..c01dfe0 100755
--- a/configure
+++ b/configure
@@ -8551,7 +8551,7 @@
 then
 	case $ac_sys_system/$ac_sys_release in
 	AIX*)
-		BLDSHARED="\$(srcdir)/Modules/ld_so_aix \$(CC) -bI:\$(srcdir)/Modules/python.exp"
+		BLDSHARED="Modules/ld_so_aix \$(CC) -bI:Modules/python.exp"
 		LDSHARED="\$(BINLIBDEST)/config/ld_so_aix \$(CC) -bI:\$(BINLIBDEST)/config/python.exp"
 		;;
 	BeOS*)
diff --git a/configure.ac b/configure.ac
index f6ca54a..1273465 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2124,7 +2124,7 @@
 then
 	case $ac_sys_system/$ac_sys_release in
 	AIX*)
-		BLDSHARED="\$(srcdir)/Modules/ld_so_aix \$(CC) -bI:\$(srcdir)/Modules/python.exp"
+		BLDSHARED="Modules/ld_so_aix \$(CC) -bI:Modules/python.exp"
 		LDSHARED="\$(BINLIBDEST)/config/ld_so_aix \$(CC) -bI:\$(BINLIBDEST)/config/python.exp"
 		;;
 	BeOS*)