Blender Git Loki

Fix T92780: Lost material in case of local object, and missing linked obdata.

By default, when syncing materials slots between object and its obdata,
the amount of slots in obdata is the reference.

Missing linked obdata is replaced by an empty placeholder that has no
material. In that specific case, if we have a valid object ID, we want
to update the (placeholder) obdata's material count from the object one,
and not the other way around.