look for final classes, and make sure they don't have protected members

Change-Id: I1fa810659bba02b61a5160dbfd8e24185ec9abf4
Reviewed-on: https://gerrit.libreoffice.org/30895Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>
Tested-by: Noel Grandin <noel.grandin@collabora.co.uk>