[mutter] screen: Fix up last commit

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

commit 0a47d135acc613cd385cba72bf1971d73a5b3542
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Fri Jun 27 14:05:38 2014 -0400

    screen: Fix up last commit
    
    Forgot to squash after building.

 src/core/screen.c |    4 +---
 1 files changed, 1 insertions(+), 3 deletions(-)
---
diff --git a/src/core/screen.c b/src/core/screen.c
index 2b00125..0195a65 100644
--- a/src/core/screen.c
+++ b/src/core/screen.c
@@ -498,9 +498,7 @@ create_guard_window (Display *xdisplay, MetaScreen *screen)
 static void
 meta_screen_set_background (MetaScreen *screen)
 {
-  XSetWindowBackground (screen->display->xdisplay,
-                        screen->xroot,
-                        BlackPixel);
+  XSetWindowBackground (screen->display->xdisplay, screen->xroot, 0x00000000);
 }
 
 MetaScreen*