[jdk11u-dev] RFR: 8261236: C2: ClhsdbJstackXcompStress test fails when StressGCM is enabled

[Sergey Nazarkin]

Hi!
I'd like to backport this changset to fix SA code after JDK-8231586.  I wasn't able to reproduce assert mentioned at the bug description even after fixing the test (inject custom vmoptions to launched SA).  Hovewer we observed the issue in the wild by investigation of core files generated by JDK15, hence it may be worth to have the fix at the jdk11 as well.

The patch applies almost cleanly, only copyright year of ImmutableOopMapSet.java should be adjusted. Tested with tier1

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Commit messages:
 - Backport 752b6df34c92c02ac0992566e3efa7bc22b96aa1

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/308/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=308&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/jdk11u-dev/pull/308.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/308/head:pull/308

PR: https://git.openjdk.java.net/jdk11u-dev/pull/308