RFR: 8238174: migrate ObjectMonitor::_owner field away from C++ volatile semantics [v2]

[Daniel D.Daugherty]

> Drop volatile from the ObjectMonitor::_owner field. Update all naked
> field loads to use the new owner_raw() accessor or the existing
> owner_is_DEFLATER_MARKER() accessor.
> 
> Testing: Mach5 Tier1,2,3 (2 & 3 are running)

Daniel D. Daugherty has updated the pull request incrementally with one additional commit since the last revision:

  @dholmes-ora CR - resolve David's comments.

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1278/files
  - new: https://git.openjdk.java.net/jdk/pull/1278/files/0f375d67..bb28666a

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1278&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1278&range=00-01

  Stats: 3 lines in 1 file changed: 1 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1278.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1278/head:pull/1278

PR: https://git.openjdk.java.net/jdk/pull/1278