notify: Remove g_object_notify_queue_from_object()

The function will not be safe with object locking in place, so we remove
it. The workaround is somewhat ugly, but it works.

https://bugzilla.gnome.org/show_bug.cgi?id=166020

gobject/gobjectnotifyqueue.c

@@ -155,13 +155,6 @@ g_object_notify_queue_add (GObject            *object,
     }
 }
 
-static inline GObjectNotifyQueue*
-g_object_notify_queue_from_object (GObject              *object,
-				   GObjectNotifyContext *context)
-{
-  return g_datalist_id_get_data (&object->qdata, context->quark_notify_queue);
-}
-
 
 G_END_DECLS