Bug 11338: prevent deletion of items that are captured for holds

Bug 11338: prevent deletion of items that are captured for holds

In C4::Items::DelItemCheck, there are two SQL queries: one to check
if item is on loan, the other if item is reserved.

Those two queries use "SELECT * FROM table", fetch the data with
"$var = $sth->fetchrow", and use "$var" as a boolean condition.

This is not correct, SQL query should be "SELECT COUNT(*) FROM table".

As a consequence, it was possible to delete an item without warning to
the operator even if it was waiting on the hold shelf or in transit to
fill a hold.

This patch corrects the SQL queries and sets my ($var) to show that
fetchrow returns an array.

Test plan :
- Set an item A onloan
- Set an item B reserved and the reserve waiting
- Go to items cataloguing : cgi-bin/koha/cataloguing/additem.pl?biblionumber=XXX
- Try to delete item A
=> You get an alert and item is not deleted
- Try to delete item B
=> You get an alert and item is not deleted

Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>
Works, and has the added bonus of being a tiny bit faster.

Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Passes t, xt and QA script tests.
Also tried deleting via batch delete - correct warnings are displayed.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>
(cherry picked from commit d000a716352fb61dc0dae7715eda15896b53b4e7)
Signed-off-by: Fridolin SOMERS <fridolin.somers@biblibre.com>