RFR: 8256302: releasing oopStorage when deflating allows for faster deleting

[Daniel D. Daugherty]

Releasing ObjectMonitor oopStorage earlier when deflating allows ObjectMonitor
deletion by a JavaThread (usually the MonitorDeflationThread) to happen while a
ThreadBlockInVM helper is in place. This should improve time-to-safepoint.

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Depends on: https://git.openjdk.org/jdk/pull/11293

Commit messages:
 - 8256302: releasing oopStorage when deflating allows for faster deleting

Changes: https://git.openjdk.org/jdk/pull/11296/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11296&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8256302
  Stats: 42 lines in 3 files changed: 32 ins; 1 del; 9 mod
  Patch: https://git.openjdk.org/jdk/pull/11296.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11296/head:pull/11296

PR: https://git.openjdk.org/jdk/pull/11296