Blender Git Loki

Fix #36541: blender internal raytrace render hangs with high ray depth. The code
here is not efficient for such cases, a ray depth can give up to 2^depth rays due
to the ray splitting in two at each depth. A proper solution requires a better
algorithm, for now I've ensured that you can at least cancel such renders. The
overhead from the extra test_break is negligible.