[jdk21u-dev] RFR: 8329109: Threads::print_on() tries to print CPU time for terminated GC threads

[Liang Mao]

Clean backport of fixing crash on Threads::print_on() .

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

Commit messages:
 - Backport c1cfb43d8de8d0eed01b9bb6aa1202dc7cbff007

Changes: https://git.openjdk.org/jdk21u-dev/pull/585/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=585&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8329109
  Stats: 4 lines in 1 file changed: 0 ins; 3 del; 1 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/585.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/585/head:pull/585

PR: https://git.openjdk.org/jdk21u-dev/pull/585