return stolen data from g_datalist_id_remove_no_notify() and

return stolen data from g_datalist_id_remove_no_notify() and

Fri Feb  4 19:36:05 2000  Tim Janik  <timj@gtk.org>

        * glib.h:
        * gdataset.c: return stolen data from g_datalist_id_remove_no_notify()
        and g_dataset_id_remove_no_notify() to avoid second lookup for common
        use.