[jdk11u-dev] RFR: 8268773: Improvements related to: Failed to start thread - pthread_create failed (EAGAIN)

[Basil Crow]

Hi all,

This pull request contains a backport of [JDK-8268773](https://bugs.openjdk.java.net/browse/JDK-8268773) (commit [e35005d5ce383ddd108096a3079b17cb0bcf76f1](https://github.com/openjdk/jdk/commit/e35005d5ce383ddd108096a3079b17cb0bcf76f1)) from the [openjdk/jdk](https://git.openjdk.java.net/jdk) repository.

There was a trivial merge conflict in `thread.hpp`. In addition, I had to drop the change to `Thread::is_JavaThread_protected` in `thread.cpp`, because `Thread::is_JavaThread_protected` does not exist on `jdk11u-dev`.

The commit being backported was authored by @dholmes-ora on July 15, 2021, and was reviewed by @tstuefe and @iklam.

See [JENKINS-65873](https://issues.jenkins.io/browse/JENKINS-65873) for the motivation behind this backport.

Thanks!

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Commit messages:
 - 8268773: Improvements related to: Failed to start thread - pthread_create failed (EAGAIN)

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/1074/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=1074&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8268773
  Stats: 69 lines in 8 files changed: 39 ins; 0 del; 30 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/1074.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/1074/head:pull/1074

PR: https://git.openjdk.java.net/jdk11u-dev/pull/1074