Bug 18152 : fix unimarc label in SetMarcUnicodeFlag

Bug 18152 : fix unimarc label in SetMarcUnicodeFlag

The standard UNIMARC requires than the 9th character (starting from 0) in
labels must be blank (while it may be 'a' in marc21)

the problem is that C4::Charset::SetMarcUnicodeFlag (called in particular when
we import a record) always add 'a' char in the 9th label'pos whereas it should
do it just for MARC21 and NORMARC (not for UNIMARC) :

C4::Charset::SetMarcUnicodeFlag add 'a' char in the 9th label character for
MARC21 and NORMARC (it's normal), but just before doing this it call
"$marc_record->encoding('UTF-8')" which is a MARC::Record function which, when
called with 'UTF-8' parameter, do only one thing : add 'a' char in the 9th
label character

This patch only removes this incorrect function call, so, when we import a bib
record in UNIMARC : it no longer adds erroneous character (this does not change
anything for MARC21 and NORMARC because SetMarcUnicodeFlag explicitly adds 'a'
char in the 9th label for them)

Signed-off-by: Alex Buckley <alexbuckley@catalyst.net.nz>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>