Bug 17420 - record export fails when itemtype on biblio - followup

Bug 17420 - record export fails when itemtype on biblio - followup

Same as previous patch for misc/export_records.pl.

Test plan :
- Use syspref item-level_itypes = biblio record
- Run misc/export_records.pl
=> Without patch you get an error : DBD::mysql::st execute failed: Unknown column 'biblioitems.itemtype' in 'where clause' ...
=> With patch you get a correct export file

Signed-off-by: Bernardo Gonzalez Kriegel <bgkriegel@gmail.com>
Export Ok, no errors.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>