[gdm] Enable silent building when available

[Ray Strode <halfline src gnome org>]

commit 9c2f1eb0f6f81a6701b8b527f0be1dde2ca4441f
Author: Ray Strode <rstrode redhat com>
Date:   Sun Sep 27 13:12:05 2009 -0400

    Enable silent building when available
    
    It's a new feature that makes spotting compiler warnings much
    easier.

 configure.ac |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 56004ed..756890a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -7,7 +7,7 @@ AC_INIT([gdm],
 AC_CONFIG_SRCDIR([daemon/gdm-manager.c])
 
 AM_INIT_AUTOMAKE([1.9 no-dist-gzip dist-bzip2 -Wall])
-
+m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])
 AM_MAINTAINER_MODE
 
 # for utmpx stuff