Fix sealed field children
Fix sealed field children

Replaced iteration to destroy every menu children data
(which used menu->children->data) by the use of a
glist and gtk_container_get_children()

https://bugzilla.gnome.org/show_bug.cgi?id=627455

Signed-off-by: Germán Póo-Caamaño <679831b636f7f6776b5d7665ebec4c0074d994a9@gnome.org>
GNOME/gnome-panel,GNOME/gnome-panel