This provide several advantages:
- more flexibility in designing unit tests
- unit tests can be glued to speed up compilation
- unit tests are compiled with same predefined macros, which is a requirement for zapcc
* Use a pseudo-random permutation of queue indices during random stealing. This ensures that all the queues are considered.
* Directly pop from a non-empty queue when we are waiting for work,
instead of first noticing that there is a non-empty queue and
then doing another round of random stealing to re-discover the non-empty
queue.
* Steal only 1 task from a remote queue instead of half of tasks.
