[gdm] Fix intltool failure in configure

[Seán de Búrca <sdeburca src gnome org>]

commit 07d5bb4c62fac0bd10c5ab8161d35214d8d28541
Author: Seán de Búrca <leftmostcat gmail com>
Date:   Tue Aug 27 08:58:02 2013 -0600

    Fix intltool failure in configure
    
    https://bugzilla.gnome.org/show_bug.cgi?id=696920

 Makefile.am |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/Makefile.am b/Makefile.am
index 7dd8bc2..3880375 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -13,6 +13,8 @@ if ENABLE_DOCUMENTATION
 SUBDIRS += docs
 endif
 
+ACLOCAL_AMFLAGS = -I m4 ${ACLOCAL_FLAGS}
+
 EXTRA_DIST = \
        MAINTAINERS             \
        ChangeLog               \