* Fix for: DefaultRwLock accumulates write-waiters, eventually fails to write lock #13163

* Comment out debug.print at the end of the last test.

* Code formatting

* - use equality test after lock/unlock rather than peeking into internals.
  however, this is still implementation specific and only done for
  DefaultRwLock.
- add num_reads maximum to ensure that reader threads stop if writer threads are
  starved
- use relaxed orderings for the read atomic counter
- don't check at the end for non-zero read ops, since the reader threads may
  only run once if they are starved

* More review changes
- Monotonic is sufficient for incrementing the reads counter