Bug 19135: Restore AllowHoldsOnPatronsPossessions behaviour

Bug 19135: Restore AllowHoldsOnPatronsPossessions behaviour

Bug caused by
  commit bc39f0392bbebaad4c083f81308f652a325be042
  Bug 14695 - Add ability to place multiple item holds on a given record per patron

Test Plan:
1) Set AllowHoldsOnPatronsPossessions to "Don't"
2) Check out an item to a patron
3) Place a hold on that item for the same patron
4) Note you are allowed to with no alert
5) Delete the hold
6) Apply this patch
7) Place a hold on that item for the same patron
8) Note you recieve an alert now

Signed-off-by: Owen Leonard <oleonard@myacpl.org>

Signed-off-by: Christopher Brannon <cbrannon@cdalibrary.org>

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>