Bug 19991: Remove warning from opac-user

Bug 19991: Remove warning from opac-user

Use of uninitialized value in split at
/home/vagrant/kohaclone/opac/opac-user.pl line 78.

Use of uninitialized value $search_query in string ne at
/home/vagrant/kohaclone/opac/opac-user.pl line 367.

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
(cherry picked from commit 38428fd71e76fdd7c9a452bc831affa03918994c)
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>