Allow OpaqueFrameException for vthreads when suspended in a loop (not at an event). This became necessary after [JDK-8386116](https://bugs.openjdk.org/browse/JDK-8386116). The ThreadReference.stop() spec allows for this:
`This method may be used to send an asynchronous exception to a virtual thread when it is suspended at an event. An implementation may support sending an asynchronous exception to a suspended virtual thread in other cases.` and `OpaqueFrameException - if the thread is a suspended virtual thread and the implementation was unable to throw an asynchronous exception from the thread's current frame` I also field [JDK-8390483](https://bugs.openjdk.org/browse/JDK-8390483) to investigate if JVMTI should remove all vthread support for StopThread when not at an event rather than having work just some of the time. The failure used to happen about 1 out of 50 runs. Tested with both platform threads and with virtual threads about 200 times each with no issues. --------- - [x] I confirm that I make this contribution in accordance with the [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai). ------------- Commit messages: - allow OpaqueFrameException for vthreads Changes: https://git.openjdk.org/jdk/pull/32403/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=32403&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8389487 Stats: 23 lines in 2 files changed: 14 ins; 1 del; 8 mod Patch: https://git.openjdk.org/jdk/pull/32403.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/32403/head:pull/32403 PR: https://git.openjdk.org/jdk/pull/32403
