Bug 6950: Hide the resort option when searching for a tag

Bug 6950: Hide the resort option when searching for a tag

If you click a link from the Tag Cloud, the results page offers the
usual select menu to resort your results. However, doing so resubmits
the search as a standard keyword search.

Test plan:
1/ Click on a tag
2/ Confirm that the resort dropdown list does not appear.

Dropdown list disappears with tags as expected.
Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>