[#33805] Only try to find a search page if the request Itemid is not a search page.

Also, find search pages by component id, not link string

Fixes this tracker item: http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=33805
You should never get to the component in the first place if it's disabled. So checking if the own component is enabled is kind of pointless. If you get here when it's disabled, something else would be broken somewhere higher up in the dispatching process.