[jdk11u-dev] RFR: 8274687: JDWP deadlocks if some Java thread reaches wait in blockOnDebuggerSuspend

[Richard Reingruber]

Hi all,

This pull request contains a backport of commit [ca2efb73](https://github.com/openjdk/jdk/commit/ca2efb73f59112d9be2ec29db405deb4c58dd435) from the [openjdk/jdk](https://git.openjdk.java.net/jdk) repository.

The commit being backported was authored by Richard Reingruber on 15 Nov 2021 and was reviewed by Chris Plummer, Serguei Spitsyn and Ralf Schmelter.

The commit applied cleanly except for one minor conflict because of the comments on the declarations of `current_ei` and `pendingStop` not present in jdk11.

The backport passed our CI testing. This includes most JCK and JTREG tiers 1-4, also in Xcomp mode, on the standard platforms and also on ppc64le and s390x.

Thanks!
Richard.

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Commit messages:
 - Backport ca2efb73f59112d9be2ec29db405deb4c58dd435

Changes: https://git.openjdk.org/jdk11u-dev/pull/1189/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=1189&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8274687
  Stats: 333 lines in 2 files changed: 314 ins; 14 del; 5 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/1189.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev pull/1189/head:pull/1189

PR: https://git.openjdk.org/jdk11u-dev/pull/1189