Bug 10664 [QA Followup] - fix error in overdue_notices.pl if there is no active currency

Bug 10664 [QA Followup] - fix error in overdue_notices.pl if there is no active currency

Fixes the following koha-qa.pl error:
 FAIL   misc/cronjobs/overdue_notices.pl
    OK     pod
    OK     forbidden patterns
    OK     valid
    FAIL   critic
               # Variables::ProhibitConditionalDeclarations:

Signed-off-by: Galen Charlton <gmc@esilibrary.com>
(cherry picked from commit e476378323eb8dd31e67e4741d271d88de61b59e)
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>
(cherry picked from commit 22f96c6ebeb77da5efe7285d1980ce705e22726e)
Signed-off-by: Bernardo Gonzalez Kriegel <bgkriegel@gmail.com>
(cherry picked from commit 22f96c6ebeb77da5efe7285d1980ce705e22726e)