Blender Git Loki

Fix T93046: Cycles world volume rendering very slow in OptiX with some scenes

With very long ray distance, OptiX ends up traversing many BVH nodes due to
a feature that improves precision. However this causes very slow rendering.

We now avoid generating such long rays by rejecting the few samples that have
long ray distances and very low probability of being generated. This should not
meaningfully affect render results.

Thanks to Sergey and Patrick for the investigation.