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 ba633da..a88b7d5 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -1418,7 +1418,7 @@
 		$(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 69dc9f5..c8c63f1 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -225,6 +225,7 @@
 Daniel Calvelo
 Tony Campbell
 Brett Cannon
+Tristan Carel
 Mike Carlton
 Pierre Carrier
 Terry Carroll
@@ -573,6 +574,7 @@
 Larry Hastings
 Tim Hatch
 Shane Hathaway
+Michael Haubenwallner
 Janko Hauser
 Rycharde Hawkes
 Ben Hayden
diff --git a/Misc/NEWS b/Misc/NEWS
index 7c6c158..07576b5 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -555,6 +555,9 @@
 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 #28444: Fix missing extensions modules when cross compiling.
diff --git a/Modules/ld_so_aix.in b/Modules/ld_so_aix.in
index add6b3e..f4eab40 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 179c198..8fcc36f 100755
--- a/configure
+++ b/configure
@@ -9226,7 +9226,7 @@
 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="\$(LIBPL)/ld_so_aix \$(CC) -bI:\$(LIBPL)/python.exp"
 		;;
 	IRIX/5*) LDSHARED="ld -shared";;
diff --git a/configure.ac b/configure.ac
index 4e55871..0886b6e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2358,7 +2358,7 @@
 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="\$(LIBPL)/ld_so_aix \$(CC) -bI:\$(LIBPL)/python.exp"
 		;;
 	IRIX/5*) LDSHARED="ld -shared";;