input-device: Ensure crossing events are paired for touch sequences

When the sequence is lifted the actor wouldn't be unset, so the corresponding
CLUTTER_LEAVE event would never be sent for the touch sequence.

https://bugzilla.gnome.org/show_bug.cgi?id=733560

clutter/clutter-input-device.c

@@ -1529,6 +1529,7 @@ _clutter_input_device_remove_event_sequence (ClutterInputDevice *device,
 
       g_hash_table_replace (device->inv_touch_sequence_actors,
                             info->actor, sequences);
+      _clutter_input_device_set_actor (device, sequence, NULL, TRUE);
     }
 
   g_hash_table_remove (device->touch_sequences_info, sequence);