main: Fix crash on shutdown

Don't let _event_del access an already freed zone.

src/bin/main.c

@@ -2393,6 +2393,9 @@ zone_del(Zone *zone)
     * their lists.
     */
 
+   evas_object_event_callback_del_full(zone->event, EVAS_CALLBACK_DEL, _event_del, zone);
+
+
    free(zone);
    zones = eina_list_remove(zones, zone);
 }