[mutter/wayland] window: Fix signedness warning

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

commit aad275b9a2fe52bf887af4a8fb37855d777dd91b
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Tue Nov 19 14:03:09 2013 -0500

    window: Fix signedness warning

 src/core/window.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/core/window.c b/src/core/window.c
index 583cbcc..e92932a 100644
--- a/src/core/window.c
+++ b/src/core/window.c
@@ -10002,7 +10002,7 @@ meta_window_handle_mouse_grab_op_event (MetaWindow         *window,
     {
     case CLUTTER_BUTTON_RELEASE:
       if (event->button.button == 1 ||
-          event->button.button == meta_prefs_get_mouse_button_resize ())
+          event->button.button == (unsigned int) meta_prefs_get_mouse_button_resize ())
         {
           meta_display_check_threshold_reached (window->display,
                                                 event->button.x,