RFR: 8345970: pthread_getcpuclockid related crashes in shenandoah tests

[William Kemper]

Clean backport.

-------------

Commit messages:
 - Backport 2ce53e88481659734bc5424c643c5e31c116bc5d

Changes: https://git.openjdk.org/shenandoah-jdk21u/pull/145/files
  Webrev: https://webrevs.openjdk.org/?repo=shenandoah-jdk21u&pr=145&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8345970
  Stats: 18 lines in 4 files changed: 15 ins; 3 del; 0 mod
  Patch: https://git.openjdk.org/shenandoah-jdk21u/pull/145.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah-jdk21u.git pull/145/head:pull/145

PR: https://git.openjdk.org/shenandoah-jdk21u/pull/145