RFR: 8359870: JVM crashes in AccessInternal::PostRuntimeDispatch [v7]

[Kevin Walls]

> ThreadDumper/ThreadSnapshot need to handle a failure to resolve the native VM JavaThread from a java.lang.Thread.  This is hard to reproduce but a thread that has since terminated can provoke a crash.  Recognise this and return a null ThreadSnapshot.

Kevin Walls 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. The pull request contains 13 additional commits since the last revision:

 - remove test definition changes
 - TLH: use cv_internal_thread_to_JavaThread()
 - Merge remote-tracking branch 'upstream/master' into 8359870_threadexited
 - Test requires: permit linux debug testing
 - comment update
 - comment update
 - newline
 - Test fails on minimal VM: require jvmti feature
 - Correct THROW macro
 - ThreadDumper thread count
 - ... and 3 more: https://git.openjdk.org/jdk/compare/80dc9acb...e2043438

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Changes:
  - all: https://git.openjdk.org/jdk/pull/25958/files
  - new: https://git.openjdk.org/jdk/pull/25958/files/d14f5228..e2043438

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=25958&range=06
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25958&range=05-06

  Stats: 7800 lines in 367 files changed: 3791 ins; 2583 del; 1426 mod
  Patch: https://git.openjdk.org/jdk/pull/25958.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25958/head:pull/25958

PR: https://git.openjdk.org/jdk/pull/25958