RFR: 8315220: Event NativeLibraryLoad breaks invariant by taking a stacktrace when thread is in state _thread_in_native [v2]

[Markus Grönlund]

> Greetings,
> 
> This change set fixes the issue of taking a JFR stack trace in the wrong thread state for the NativeLibraryLoad and NativeLibraryUnload events.
> 
> A follow-up change set, [JDK-8315364](https://bugs.openjdk.org/browse/JDK-8315364) will add assertions to the JFR stack trace code to help find similar issues earlier.
> 
> There are a few additional improvements:
> 
> The event declaration in metadata.xml now includes the generating thread since a stack trace without the generating thread is subpar.
> 
> In os_linux.cpp, the NativeLibraryLoad event was located after the call to dlopen(), which means that the event, declared durational, fails to capture the duration of the call.
> 
> Finally, the test is extended to validate the captured stack trace.
> 
> Testing: jdk_jfr, stress testing
> 
> Thanks
> Markus

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

  renaming and commentary

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/15535/files
  - new: https://git.openjdk.org/jdk/pull/15535/files/aa4bc48a..b0094b7f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15535&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15535&range=00-01

  Stats: 32 lines in 2 files changed: 11 ins; 0 del; 21 mod
  Patch: https://git.openjdk.org/jdk/pull/15535.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15535/head:pull/15535

PR: https://git.openjdk.org/jdk/pull/15535