RFR: 8315364: Assert thread state invariant for JFR stack trace capture [v2]

[Markus Grönlund]

> Greetings,
> 
> A JavaThread running in state _thread_in_native cannot capture a JFR stack trace because tagging of artefacts (klasses, methods, etc.) is a function of an epoch, which evolves during safepoints.
> 
> Asserting this invariant would have helped prevent the issue detailed in [JDK-8315220](https://bugs.openjdk.org/browse/JDK-8315220).
> 
> Testing: jdk_jfr
> 
> Thanks
> Markus

Markus Grönlund has updated the pull request incrementally with one additional commit since the last revision:

  hide set_large() from public API

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/15491/files
  - new: https://git.openjdk.org/jdk/pull/15491/files/1e439601..194f1c75

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15491&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15491&range=00-01

  Stats: 16 lines in 1 file changed: 8 ins; 8 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/15491.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15491/head:pull/15491

PR: https://git.openjdk.org/jdk/pull/15491