[gtkglext] Replace erroneously removed enable-rebuilds argument and _targetlib substitutions.

[Braden McDaniel <bradenmcd src gnome org>]

commit d1d693a80cb84452d6d28e3d70867fd3cb7f7018
Author: Braden McDaniel <braden bolt endoframe net>
Date:   Fri Dec 18 02:41:19 2009 -0500

    Replace erroneously removed enable-rebuilds argument and _targetlib substitutions.

 configure.ac |   27 +++++++++++++++++++++++++++
 1 files changed, 27 insertions(+), 0 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 722dac4..120cc9e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -296,6 +296,33 @@ AC_CHECK_FUNCS([memset sqrt strchr strrchr strstr])
 
 LIBS="$save_LIBS"
 
+# define a MAINT-like variable REBUILD which is set if Perl
+# and awk are found, so autogenerated sources can be rebuilt
+
+AC_ARG_ENABLE([rebuilds],
+              [AS_HELP_STRING([--disable-rebuilds],
+                              [disable all source autogeneration rules])], ,
+              [enable_rebuilds=yes])
+
+REBUILD=\#
+if test "x$enable_rebuilds" = "xyes" && \
+     test -n "$PERL" && \
+     $PERL -e 'exit !($] >= 5.002)' > /dev/null 2>&1 ; then
+  REBUILD=
+fi
+AC_SUBST([REBUILD])
+
+case $gdktarget in
+  x11|win32) ;;
+  *) AC_MSG_ERROR([Invalid target for GDK: use x11 or win32.]);;
+esac
+AC_SUBST([gdktarget])
+
+gdkglext_targetlib=libgdkglext-$gdktarget-$GTKGLEXT_API_VERSION.la
+gtkglext_targetlib=libgtkglext-$gdktarget-$GTKGLEXT_API_VERSION.la
+
+AC_SUBST([gdkglext_targetlib])
+AC_SUBST([gtkglext_targetlib])
 
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 # Checks for Window System