[jdk21u-dev] RFR: 8320309: AIX: pthreads created by foreign test library don't work as expected

[Christoph Langer]

Hi all,

This pull request contains a backport of [JDK-8320309](https://bugs.openjdk.org/browse/JDK-8320309), commit [8b47a149](https://github.com/openjdk/jdk/commit/8b47a14958913c70291d46afdde4e527f9bdc91a) from the [openjdk/jdk](https://git.openjdk.org/jdk) repository.

The commit being backported was authored by Varada M on 22 Nov 2023 and was reviewed by Martin Doerr, Matthias Baesken and Thomas Stuefe.

Thanks!

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Commit messages:
 - Backport 8b47a14958913c70291d46afdde4e527f9bdc91a

Changes: https://git.openjdk.org/jdk21u-dev/pull/159/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=159&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8320309
  Stats: 6 lines in 1 file changed: 5 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/159.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/159/head:pull/159

PR: https://git.openjdk.org/jdk21u-dev/pull/159