Blender Git Loki

Moar debug printf...

Merge branch 'blender2.8' into tmp-debug-filebrowser

Fix T52116: Blender internal BVH build crash in degenerate cases.

Fix (unreported) seldom crash when using previews in filebrowser.

Hopefully fix it actually, at least could not reproduce it anymore with
that changen, but Was already quite hard to trigger before.
We need a memory barrier at this allocation, otherwise it might happen
after preview gets added to done queue, so preview could end up being
freed twice, leading to crash.

Debug prints to debug 2.8 filebrowser bug not always working with previews