mark numbers as untranslatable

Change-Id: I6306ad4ecb4a3450f1ae518d8b8c88531695fe12
Reviewed-on: https://gerrit.libreoffice.org/13075
Reviewed-by: Andras Timar <andras.timar@collabora.com>
Tested-by: Andras Timar <andras.timar@collabora.com>