Bug 8915: Followup FIX QA issues

Bug 8915: Followup FIX QA issues

Before this patch:
* misc/maintenance/fix_mysql_constraints.pl                                FAIL
    pod                         FAIL
        *** ERROR: unterminated B<...>  in file misc/maintenance/fix_mysql_constraints.pl
    forbidden patterns          OK
    valid                       OK
    critic                      FAIL
        "require" statement with library name as string at line 25, column 12. Use a bareword instead.

+ I add a die on the open statement

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Passed-QA-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>