Blender Git Loki

Fix T62318: Blender crash whith 'corrupt' customdata (CD_BWEIGHT).

Mistake in rBab0bc65c24bd, in conversion of static 'common' sets of
masks, BWEIGHT slipped in CD_MASK_MESH (probably from copy/paste from
CD_MASK BAREMESH).

Note that having it in CD_MASK_BAREMESH but not CD_MASK_MESH looks rather
counter-intuitive, but this is not the time for that kind of cleanup.

Went over whole conversion again, and found two other mistakes, should
really have recheck that before committing...