events: process CLUTTER_TOUCH_CANCEL

These events might be emitted from the window manager/compositor, they
need to be transmitted to widgets.

https://bugzilla.gnome.org/show_bug.cgi?id=680752

clutter/clutter-main.c

@@ -2667,6 +2667,7 @@ _clutter_process_event_details (ClutterActor        *stage,
 
       /* fallthrough from motion */
       case CLUTTER_TOUCH_BEGIN:
+      case CLUTTER_TOUCH_CANCEL:
       case CLUTTER_TOUCH_END:
         {
           ClutterActor *actor;
@@ -2717,9 +2718,6 @@ _clutter_process_event_details (ClutterActor        *stage,
           break;
         }
 
-      case CLUTTER_TOUCH_CANCEL:
-        break;
-
       case CLUTTER_STAGE_STATE:
         /* fullscreen / focus - forward to stage */
         event->any.source = stage;