In preparation to get rid of the per call locally created
SvNumberFormatter instances..

Change-Id: Ic7db3bbb655aa18e939f5722964655a20f2eadf2
Reviewed-on: https://gerrit.libreoffice.org/45227Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Eike Rathke <erack@redhat.com>