Bug 16950: Serials subscriptions advanced search shows '0 found' pre-search

Bug 16950: Serials subscriptions advanced search shows '0 found' pre-search

To test:
1) Go to Serials
2) Click Advanced Search in the toolbar at the top
3) Notice heading says Serials subscriptions (0 found) before a search has even happened
4) Apply patch and click Advanced Search again
5) Heading should now say Serials subscriptions search
6) Submit search
7) Heading should say how many subscriptions your search found (like before)

Sponsored-by: Catalyst IT
Signed-off-by: Marc <veron@veron.ch>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit 031219935c41643734de7836ed86b59ed6be5fd1)
Signed-off-by: Frédéric Demians <f.demians@tamil.fr>