RFR: 8369991: Thread blocking during JFR emergency dump must be in safepoint safe state

[Markus Grönlund]

Greetings,

A tiny adjustment to the fix in https://bugs.openjdk.org/browse/JDK-8369255.

A JavaThread must be in a safe safepoint state before taking an infinite nap; for convenience, it goes to _thread_in_native.

Testing: jdk_jfr

Thanks
Markus

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Commit messages:
 - 8369991

Changes: https://git.openjdk.org/jdk/pull/27862/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27862&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8369991
  Stats: 10 lines in 1 file changed: 6 ins; 1 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/27862.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27862/head:pull/27862

PR: https://git.openjdk.org/jdk/pull/27862