Bug 14115: Silence warnings in t/Label*

Bug 14115: Silence warnings in t/Label*

Two functions were triggering noisy warnings while testing:
_get_text_fields and _split_lccn.

TEST PLAN
----------
1) $ prove t/Label*
   -- several warnings
2) apply patch
3) $ prove t/Label*
   -- no warnings
4) koha qa test tools.

Signed-off-by: Bernardo Gonzalez Kriegel <bgkriegel@gmail.com>
Nicer, no koha-qa errors

Signed-off-by: Aleisha <aleishaamohia@hotmail.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>