RFR: 8245877: assert(_value != __null) failed: resolving NULL _value in JvmtiExport::post_compiled_method_load

[Leonid Mesnik]

The crash happens because nmethod might become a zombie before it is enqueued in JvmtiDeferredEventQueue or after it is dequeued from it. The crash is reproduced by serviceability/jvmti/CompiledMethodLoad/Zombie.java. However, it takes ~3K  runs to hit it. I verified the fix by running this test >100K on each platform. Also, I verified that protecting in 'void JvmtiDeferredEventQueue::post(JvmtiEnv* env)' is not enough.

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Commit messages:
 - fix in problemlist.txt
 - Merge branch 'master' of https://github.com/openjdk/jdk into 8245877
 - ident fixed.
 - test unproblemlisted.
 - fix

Changes: https://git.openjdk.java.net/jdk/pull/4602/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4602&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8245877
  Stats: 9 lines in 4 files changed: 5 ins; 2 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4602.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4602/head:pull/4602

PR: https://git.openjdk.java.net/jdk/pull/4602