mark numbers as untranslatable

Change-Id: Ib6aa1a53bef3aefd9266b87340a5d787d99e600a
Reviewed-on: https://gerrit.libreoffice.org/13252
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>