RFR: 8365192: post_meth_exit should be in vm state when calling get_jvmti_thread_state [v6]

[Leonid Mesnik]

> This is the second attempt to fix method `post_meth_exit` to correctly set state and preserve result.
> The related fix here:
> https://github.com/openjdk/jdk/commit/b7b64bb6c800b45e32ff37b1b92b5927a3b3fb56
> Hope fix became clarere now.
> 
> There 2 problems in this post_meth_exit:
> 1) The result is preserved only if `state->is_enabled(JVMTI_EVENT_METHOD_EXIT)` however transition in the JRT_BLOCK_END happens always. So there is a risk of loosing method results in the interp_only mode.
> 2) The method `get_jvmti_thread_state` should be called when thread is in vm state only.
> 
> The fix adds `post_method_exit_transition` to have single exit point with oop restoration.

Leonid Mesnik has updated the pull request incrementally with one additional commit since the last revision:

  comments fixed.

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/27112/files
  - new: https://git.openjdk.org/jdk/pull/27112/files/ea941c2d..03c172a9

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27112&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27112&range=04-05

  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/27112.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27112/head:pull/27112

PR: https://git.openjdk.org/jdk/pull/27112