RFR: 8267842: SIGSEGV in get_current_contended_monitor

[Martin Doerr]

We need a fix for crashes in get_current_contended_monitor due to concurrent modification of memory locations which are not declared volatile. See bug for details.

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

Commit messages:
 - 8267842: SIGSEGV in get_current_contended_monitor

Changes: https://git.openjdk.java.net/jdk/pull/4224/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4224&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8267842
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4224.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4224/head:pull/4224

PR: https://git.openjdk.java.net/jdk/pull/4224