[cogl] build: Create the libtool file early as it's used by AS_GLIBCONFIG

[Robert Bragg <rbragg src gnome org>]

commit ae457e0e2463bcec4f5891778e8ada9924f91be7
Author: Damien Lespiau <damien lespiau intel com>
Date:   Wed Sep 19 13:50:04 2012 +0100

    build: Create the libtool file early as it's used by AS_GLIBCONFIG
    
    glib's configure.ac uses libtool to determine the extension of shared
    libraries. So let's generate the libtool file early in configure.
    
    Reviewed-by: Robert Bragg <robert linux intel com>

 configure.ac |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index fe39d76..ced55bf 100644
--- a/configure.ac
+++ b/configure.ac
@@ -160,6 +160,9 @@ dnl AC_PROG_LIBTOOL
 dnl LIBTOOL="$LIBTOOL --preserve-dup-deps"
 LT_PREREQ([2.2.6])
 LT_INIT([disable-static])
+dnl when using libtool 2.x create libtool early, because it's used in the
+dnl internal glib configure (as-glibconfig.m4)
+m4_ifdef([LT_OUTPUT], [LT_OUTPUT])
 
 dnl ================================================================
 dnl See what platform we are building for