Bug 8474: Holds done by librarians cause silent errors in koha-error_log, placereques...

Bug 8474: Holds done by librarians cause silent errors in koha-error_log, placerequest.pl -> $checkitem

Squashed this rogue variable initialization

Test plan:
1/ Place a hold at a biblio level (on the next available item)
2/ Without this patch you get
placerequest.pl: Use of uninitialized value $checkitem in string ne at /home/koha/src/reserve/placerequest.pl line 75.
placerequest.pl: Use of uninitialized value $checkitem in string ne at /home/koha/src/reserve/placerequest.pl line 101.

Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Fixed a tab.

Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>