RFR: 8338934: vmTestbase/nsk/jvmti/*Field*Watch/TestDescription.java tests timeout intermittently [v2]

[Leonid Mesnik]

> The tests time out because of dedlock of  of the thread that is in transition and thread changing field watches. 
> 
> They use JvmtiThreadState_lock and JvmtiVTMSTransitionDisabler.
> 
> The change field watch require disabler, but attempt to use it only when already locked in 
> 
> void
> JvmtiEventController::change_field_watch(jvmtiEvent event_type, bool added) {
>   MutexLocker mu(JvmtiThreadState_lock);
>   JvmtiEventControllerPrivate::change_field_watch(event_type, added);
> }
> 
> 
> while it is needed to first disable transitions and then try to use JvmtiThreadState_lock.
> I quickly looked that most of jvmti methods do it already. Also moved disabler into jvmtiEmv.cpp to be more consistent with other methods.
> 
> 
> I was able to verify my fix in loom repo locally. and run tier1 + tier5-svc testing in jdk.

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

  fixed spaces

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/20776/files
  - new: https://git.openjdk.org/jdk/pull/20776/files/89e57b0d..cde6c486

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20776&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20776&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/20776.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20776/head:pull/20776

PR: https://git.openjdk.org/jdk/pull/20776