[metacity] Use -Werror only when --enable-maintainer-mode is used

[Vincent Untz <vuntz src gnome org>]

commit dbfe9378c20cc11aa1cb276badcb8f87172eb6a1
Author: Vincent Untz <vuntz gnome org>
Date:   Sat Sep 18 12:14:14 2010 +0200

    Use -Werror only when --enable-maintainer-mode is used
    
    This means that tarballs will not fail on warnings by default, while
    building from git will.

 configure.in |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)
---
diff --git a/configure.in b/configure.in
index 92a914c..acdc854 100644
--- a/configure.in
+++ b/configure.in
@@ -522,7 +522,10 @@ fi
 
 # Warnings are there for a reason
 if test "x$GCC" = "xyes"; then
-  CFLAGS="$CFLAGS -Wall -Werror -ansi"
+  CFLAGS="$CFLAGS -Wall -ansi"
+  if test "x$enable_maintainer_mode" = "xyes"; then
+    CFLAGS="$CFLAGS -Werror"
+  fi
 fi
 
 # Use gnome-doc-utils: