Blender Git Loki

Fix part of T63595: generated texture coordinates don't stick to deforming mesh

Always compute CD_ORCO undeformed coordinates now for rendering, same as before.
There is still a refresh issue to be fixed, when switching from solid to textured
mode in the viewport.

Computing such undeformed coordinates can be expensive and is not actually needed
if the mesh is only using e.g. UV maps. This was the same in 2.79, at least now we
are skipping the computation when there are no deforming mdifiers on the mesh.