Bug 5834: Holds link missing when 942$c is not for loan

Bug 5834: Holds link missing when 942$c is not for loan

Adds a check for item-level_itypes system preference. Note that this only
applies to the search results screens.

To test:
1) Set item-level_itypes to 'specific item'
2) Create record and set 942$c to an itype that is marked not for loan
3) Create item with itype not marked 'not for loan'
Current behaviour: Holds link is not shown, sys pref setting doesn't matter

After patch: Holds link is shown
- when item-level_itype is 'specific item'
- when item-level_itype is 'biblio record' and 942$c itype is for loan

Holds link is not shown
- when item-level_itype is 'biblio record' and 942$c is not for loan

Signed-off-by: Jared Camins-Esakov <jcamins@bywatersolutions.com>
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>