Bug 11412: fix potential bulkmarcimport crash when searching for duplicates in author...

Bug 11412: fix potential bulkmarcimport crash when searching for duplicates in authorities

bulkmarcimport.pl can crash when searching for duplicates if the 005
field from the incoming or local record is not defined. This patch
fixes it.

Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>
Test plan
1/ Create a record with no 005 field
2/ Try to import it checking for duplicates, notice it crashes
3/ Try with a record with a 005 field, but the one in Koha missing
one, still crashes
4/ Apply patch
5/ No more crash

Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Passes all tests and QA script.
Patch fixes the problem described for importing authorities
with the bulkmarcimport.pl when trying to match with existing
records.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>
(cherry picked from commit 28d97e322805a42680527232b151754b4778aed8)
Signed-off-by: Fridolin SOMERS <fridolin.somers@biblibre.com>