[mutter/wayland] backend: Fix warning

[Jasper St. Pierre <jstpierre src gnome org>]

commit 67b6737b271fa777342fcff52deadd08479eec40
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Tue Apr 1 14:04:53 2014 -0400

    backend: Fix warning

 src/backends/meta-backend.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/src/backends/meta-backend.c b/src/backends/meta-backend.c
index b5ea43d..b8a6dc1 100644
--- a/src/backends/meta-backend.c
+++ b/src/backends/meta-backend.c
@@ -32,6 +32,7 @@
 #include <clutter/x11/clutter-x11.h>
 
 #include "backends/native/meta-weston-launch.h"
+#include <meta/util.h>
 
 /* Mutter is responsible for pulling events off the X queue, so Clutter
  * doesn't need (and shouldn't) run its normal event source which polls