RFR: 8368621: In ASAN builds, attached non-main threads should have meaningful native names

Sat Sep 27 12:00:56 UTC 2025

See issue description and discussion. We set the thread name at the OS level, but only for ASAN builds, since outside of that narrow use case we consider attached threads to be owned by the application, not us, so we don't interfere with it.

Tested manually with an ASAN build and a custom java launcher that attaches some native threads.

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Commit messages:
 - start

Changes: https://git.openjdk.org/jdk/pull/27535/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27535&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8368621
  Stats: 11 lines in 1 file changed: 11 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/27535.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27535/head:pull/27535

PR: https://git.openjdk.org/jdk/pull/27535