RFR: 8256474: Migrate Mutex _owner accesses to use Atomic operations [v2]

[David Holmes]

> Simple update to move away from volatile fields and use Atomic::load/store on racy accesses.
> 
> Thanks,
> David

David Holmes has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - Fixed comment typo
 - Merge branch 'master' into 8256474
 - 8256474: Migrate Mutex _owner accesses to use Atomic operations

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1402/files
  - new: https://git.openjdk.java.net/jdk/pull/1402/files/175e5954..fa203cb5

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1402&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1402&range=00-01

  Stats: 1337 lines in 38 files changed: 648 ins; 397 del; 292 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1402.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1402/head:pull/1402

PR: https://git.openjdk.java.net/jdk/pull/1402