[jdk8u-dev] RFR: 8313081: MonitoringSupport_lock should be unconditionally initialized after 8304074

[Paul Hohensee]

Follow-on bug fix for [JDK-8304074](https://bugs.openjdk.org/browse/JDK-8304074) backport. Unclean backport from 11u, see https://github.com/openjdk/jdk11u-dev/pull/2287. Other than file location and context, the lock definition macro changed between 8 and 11, so the definition of MonitoringSupport_lock is different.

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Depends on: https://git.openjdk.org/jdk8u-dev/pull/392

Commit messages:
 - Merge branch 'backport-8304074' into backport-8313081
 - Merge branch 'backport-8304074' into backport-8313081
 - Backport a9d21c61fb12a11e18c6bb8aa903e5a8e42473f1

Changes: https://git.openjdk.org/jdk8u-dev/pull/393/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=393&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8313081
  Stats: 17 lines in 3 files changed: 12 ins; 2 del; 3 mod
  Patch: https://git.openjdk.org/jdk8u-dev/pull/393.diff
  Fetch: git fetch https://git.openjdk.org/jdk8u-dev.git pull/393/head:pull/393

PR: https://git.openjdk.org/jdk8u-dev/pull/393