Issue #25825: Fix references to $(LIBPL) installation path on AIX

In Subversion r86731, the path was changed from $(BINLIBDEST)/config to
$(LIBDEST)/config-$(LDVERSION).
diff --git a/configure b/configure
index d45dd65..f5ff3ce 100755
--- a/configure
+++ b/configure
@@ -9040,7 +9040,7 @@
 	case $ac_sys_system/$ac_sys_release in
 	AIX*)
 		BLDSHARED="\$(srcdir)/Modules/ld_so_aix \$(CC) -bI:\$(srcdir)/Modules/python.exp"
-		LDSHARED="\$(BINLIBDEST)/config/ld_so_aix \$(CC) -bI:\$(BINLIBDEST)/config/python.exp"
+		LDSHARED="\$(LIBPL)/ld_so_aix \$(CC) -bI:\$(LIBPL)/python.exp"
 		;;
 	IRIX/5*) LDSHARED="ld -shared";;
 	IRIX*/6*) LDSHARED="ld ${SGI_ABI} -shared -all";;