Bug 6911: Remember search terms in the log viewer tool

Bug 6911: Remember search terms in the log viewer tool

The modules and actions selected by the user are now selected when a
log search is done.
Note that this patch also add the multiple attribute to the actions
select in order to add the ability to select several actions.
The code to do that already existed.

Test plan:
1/ Go on the log viewer tool (tools/viewlog.pl)
2/ Launch a search with modules and actions selected.
3/ Confirm that the values you have selected is still selected after the
search.

Patch works 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>