[jdk13u-dev] RFR: 8261236: C2: ClhsdbJstackXcompStress test fails when StressGCM is enabled

[Sergey Nazarkin]

I'd like to backport that fixes SA after changes made by JDK-8231586 in OopMapValue. The patch applies almost cleanly except copyright year at ImmutableOopMapSet.java. Tested with hotspot/tier1. I was not able to reproduce the issue with provided instruction due to test difference.  Quick fix of the test shows no exception at jhsdb as well. Hovewer this changeset need to be integrated due to obvious dependency from JDK-8231586

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

Commit messages:
 - Backport 752b6df34c92c02ac0992566e3efa7bc22b96aa1

Changes: https://git.openjdk.java.net/jdk13u-dev/pull/256/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk13u-dev&pr=256&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8261236
  Stats: 58 lines in 3 files changed: 12 ins; 28 del; 18 mod
  Patch: https://git.openjdk.java.net/jdk13u-dev/pull/256.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk13u-dev pull/256/head:pull/256

PR: https://git.openjdk.java.net/jdk13u-dev/pull/256