Fix deadlock with debug agent callbackLock. Details in first comment. Tested by running all jdi, jdwp, and jdb tests with and without virtual threads about 40 times. The testing was initially done with my hack to force the self suspend (see the first comment in the CR), and then I did final testing without it. I also did final testing with all tier5 svc tests.
------------- Commit messages: - Fix deadlock with callbackLock. Changes: https://git.openjdk.org/jdk/pull/20282/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20282&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8332738 Stats: 44 lines in 5 files changed: 29 ins; 3 del; 12 mod Patch: https://git.openjdk.org/jdk/pull/20282.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/20282/head:pull/20282 PR: https://git.openjdk.org/jdk/pull/20282
