RFR: 8307068: store a JavaThread* in the java.lang.Thread object after the JavaThread* is added to the main ThreadsList [v2]

[Daniel D. Daugherty]

> A small fix to store a JavaThread* in the java.lang.Thread object after the JavaThread*
> is added to the main ThreadsList. Also adds the following:
> - `java_lang_Thread::thread_acquire()`
> - `java_lang_Thread::release_set_thread()`
> 
> And uses them on an as-needed basis.

Daniel D. Daugherty 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.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13723/files
  - new: https://git.openjdk.org/jdk/pull/13723/files/4b0833ea..4b0833ea

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13723&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13723&range=00-01

  Stats: 0 lines in 0 files changed: 0 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/13723.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13723/head:pull/13723

PR: https://git.openjdk.org/jdk/pull/13723