0e1ee29f77
When building without TBB use native to the platform spin lock implementation. For Windows it is an atomic-based busy-wait, for Linux it is pthreads' spin lock. For macOS it is a mutex lock. The reason behind this is to stop using atomics library which has been declared deprecated in SDK version 10.12. So this changes fixes a lot of noisy warnings on the newer SDK. Differential Revision: https://developer.blender.org/D8180