Blender Git Loki

Fix T43596: Refraction BSDF crashes blender on pre-sse4 CPU

This is the same issue T43475: SSE4 code is more robust to non-finite values
in the ray origin/direction. So for now added a check before doing BVH traversal
for pre-SSE4 CPUs.

For sure actual root of the issue is a bit different and much more tricky to
solve, especially without disturbing render results too much. Still looking
into this.

In any case, it's kinda fine to have such a check, we might later make it to be
a kernel_assert() instead of just a return.