las3_pub / predictable_parallel_patterns

We fixed the bug in tsan causing it to crash after creating/deleting many fibers, because of that there is no need for this cache mechanism (you have to use the most recent clang build with the patch for it to work thought).

Tsan does not cope well with rapidely destroyed/created fibers. As it is currently too much effort to fully investigate the tsan issue we work around it by caching the shourt lived fibers based on their stack base address. This allows us to use thread sanitizer for now.

The rationale to do an custom implementation is that the existing solutions are quite a bit slower and/or require more memory.