[master] RFR: 8319724: [Lilliput] ParallelGC: Forwarded objects found during heap inspection

[Roman Kennke]

This is the Lilliput variant of [JDK-8319376](https://bugs.openjdk.org/browse/JDK-8319376). With Lilliput we need special treatment of the fix, because the iterator needs to access the Klass*, which it can only get via the forwardee.

Testing:
 - [x] gc/logging/TestUnifiedLoggingSwitchStress.java +UseParallelGC +UCOH
 - [x] gc/logging/TestUnifiedLoggingSwitchStress.java +UseParallelGC -UCOH
 - [ ] hotspot_gc +UCOH
 - [ ] tier1 +UCOH
 - [ ] tier2 +UCOH

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Commit messages:
 - 8319724: [Lilliput] ParallelGC: Forwarded objects found during heap inspection

Changes: https://git.openjdk.org/lilliput/pull/116/files
 Webrev: https://webrevs.openjdk.org/?repo=lilliput&pr=116&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8319724
  Stats: 31 lines in 2 files changed: 28 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/lilliput/pull/116.diff
  Fetch: git fetch https://git.openjdk.org/lilliput.git pull/116/head:pull/116

PR: https://git.openjdk.org/lilliput/pull/116