[gtk-engines] Enable silent build with automake 1.11

[Benjamin Berg <bberg src gnome org>]

commit 97e5a62b40294fdba4cc76b60cd38fc153202881
Author: Diego Escalante Urrelo <diegoe gnome org>
Date:   Tue Dec 1 00:19:18 2009 -0500

    Enable silent build with automake 1.11

 configure.ac |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 7ba482e..3083cdc 100644
--- a/configure.ac
+++ b/configure.ac
@@ -4,6 +4,9 @@ AC_CONFIG_SRCDIR([README])
 
 AM_INIT_AUTOMAKE
 
+# Use AM_SILENT_RULES if present
+m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])
+
 dnl Initialize maintainer mode
 AM_MAINTAINER_MODE