regression from

    commit 79800559
    convert MT_ constants to scoped enum

The original code used bit-wise operations and some clever constant
values, which I did not convert correctly

Change-Id: I2fcd9e2584638d4a690773ef3f178415153b8b19
Reviewed-on: https://gerrit.libreoffice.org/55596Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>