[#32064] Fix small issue with mod_menu (backend)

If not have access to com_media the menu display a wrong separator:

![menu user problem](https://f.cloud.github.com/assets/441774/1103562/cb4ab2d2-18b2-11e3-8e6d-c2d67f8d0774.png)

Tracker: #32064
http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=32064&start=0