RFR: 8365726: Test crashed with assert in C1 thread: Possible safepoint reached by thread that does not allow it

[Igor Veresov]

`TrainingData_lock` guards a non-thread safe container and is only locked for a short time. Allow it to skip the safepoint check.

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Commit messages:
 - Don't check for safepoint

Changes: https://git.openjdk.org/jdk/pull/26964/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26964&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8365726
  Stats: 3 lines in 2 files changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/26964.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26964/head:pull/26964

PR: https://git.openjdk.org/jdk/pull/26964