las3_pub / predictable_parallel_patterns

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.

Older CMAKE versions wont work with export targets in different directories. For now we simply add the context_switcher manually to the export target of pls.

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