Blender Git Loki

Fix T74939: Random Walk subsurface appearance in OptiX does not match other engines

Random Walk subsurface scattering did look different with OptiX because transmittance is
calculated based on the hit distance, but the OptiX implementation of `scene_intersect_local`
would return the distance in world space, while the Cycles BVH version returns it in object
space. This fixes the problem by simply skipping the object->world transforms in all the
places using the result of `scene_intersect_local` with OptiX.

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D7232