Bug 22969: fix biblionumber on 001 in UNIMARC XSLT

Bug 22969: fix biblionumber on 001 in UNIMARC XSLT

In UNIMARC default configuration the 001 is linked to biblio.biblionumber.
In some XSLT files, 090$a is used.
This is by default biblioitems.biblionumber so it usually works but it may not be the same and var biblionumber is used to create hyperlinks to record detail page.

Test plan :
1) Use UNIMARC database
2) Set default in all XSLT system preferences
3) At OPAC, perform a search and click on a result
4) Check displayed page shows the correct biblio record
5) Same at intranet

Signed-off-by: Bernardo Gonzalez Kriegel <bgkriegel@gmail.com>
Tested on clean UNIMARC install.
Before insert new records: "alter table biblioitems AUTO_INCREMENT = 5"
Added two records, with result:
+--------------+------------------+
| biblionumber | biblioitemnumber |
+--------------+------------------+
|            1 |                5 |
|            2 |                6 |
+--------------+------------------+
Without patch, OPAC results shows for first record
  http://opac/cgi-bin/koha/opac-detail.pl?biblionumber=5, Wrong!
with patch result is correct

Works, no errors

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Joy Nelson <joy@bywatersolutions.com>