RFR: 8345970: pthread_getcpuclockid related crashes in shenandoah tests [v2]

[William Kemper]

> Clean backport.

William Kemper has updated the pull request incrementally with one additional commit since the last revision:

  Do not use API that does not exist in 21

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

Changes:
  - all: https://git.openjdk.org/shenandoah-jdk21u/pull/145/files
  - new: https://git.openjdk.org/shenandoah-jdk21u/pull/145/files/0c969cc4..8401a30a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=shenandoah-jdk21u&pr=145&range=01
 - incr: https://webrevs.openjdk.org/?repo=shenandoah-jdk21u&pr=145&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 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