5659c8e0bf
Although not using multithreading, the `thread` parameter in the `BVHTree_OverlapCallback` callback always returned a value between the "number of threads". This parameter should always be 0 in such cases. Also a `BLI_Stack` was created for each "thread" and used. This small overhead is no longer seen. Differential Revision: https://developer.blender.org/D6510