This sub-task captures updates to the baseline code that came up
during the Async Monitor Deflation project.

The changes include:

- set_owner() does not need to set _recursions and remove
  the verbose commentary since it is now a simple setter
- remove unnecessary set_owner(NULL) calls:
  - in ObjectSynchronizer::omFlush()
  - in ObjectSynchronizer::inflate(for CASE: neutral)
- remove unnecessary '_recursions = 0' settings that are
  handled by an earlier Recycle() call
- is_busy() diagnostic mesg support:
  - add ObjectMonitor::is_busy_to_string() and use it
    in assert() and guarantee() calls
- remove assert()'s that check core results like Atomic::cmpxchg()
  (Thanks Robbin!)
- remove some stale comments
- fix some bad comments in ObjectSynchronizer::omFlush() that
  came from an old fix that I pushed in 2015 (JDK-8073165).
- update 'monitorinflation' logging to include new is_busy_to_string() output