Blender Git Loki

Cycles: Restore integrator's AA samples update

The AA samples are not communicated from BlenderSync to the integrator.

This is something what should become more explicit or clear: maybe set
AA samples together with diffuse/glossy/etc in the sync, and/or make it
happen from `Session::set_samples()`.

For now restore old style code which happens in `Session::update_scene`
but cover it with comment and do it without condition.