crash in tools->options->advanced

regression from...

commit 06562c678410e425de629109ce92933c2d89a8f6
Date:   Sat Oct 18 10:36:36 2014 +0200

    convert SV_BMP_ constants to enum

    Change-Id: I46cb7f649fa44d8967e0e7da03583157d2706f05
    Reviewed-on: https://gerrit.libreoffice.org/12018
    Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
    Tested-by: Noel Grandin <noelgrandin@gmail.com>

Change-Id: I29486e8fe17d9e06e01c33f93d99ffc6ae3d017c