mark numbers as untranslatable

Change-Id: Iad5d9c5e4b7e82f5809b7aa04f782a2f4e26585c
Reviewed-on: https://gerrit.libreoffice.org/13074
Reviewed-by: Andras Timar <andras.timar@collabora.com>
Tested-by: Andras Timar <andras.timar@collabora.com>