Bug 5333 - z3950 normalization should apply only on UNIMARC

Bug 5333 - z3950 normalization should apply only on UNIMARC

It's been a while since this bug is around. This normalization is only
used for UNIMARC and yields a fatal error when those variables are set
on (at least) MARC21 setups.

Regards
To+

Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Amended patch: update comment
Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>
Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>