[jdk13u-dev] RFR: 8173658: JvmtiExport::post_class_unload() is broken for non-JavaThread initiators

[Ekaterina Vergizova]

I'd like to backport 8173658 to 13u for parity with 11u.
The patch applies cleanly, CSR for the fix is approved for 13u: JDK-8260003.
Tested with tier1 and jvmti tests.

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Commit messages:
 - Backport d1d57d944632b6539ba1fcd654b4c7bd889ff604

Changes: https://git.openjdk.java.net/jdk13u-dev/pull/81/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk13u-dev&pr=81&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8173658
  Stats: 123 lines in 9 files changed: 72 ins; 37 del; 14 mod
  Patch: https://git.openjdk.java.net/jdk13u-dev/pull/81.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk13u-dev pull/81/head:pull/81

PR: https://git.openjdk.java.net/jdk13u-dev/pull/81