[lworld] RFR: 8355560: SetTag/GetTag should consider equal value objects as the same object

[Alex Menkov]

Fixes SetTag/GetTag JVMTI functions so they consider equal value object as a single object.

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Commit messages:
 - fix

Changes: https://git.openjdk.org/valhalla/pull/1444/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1444&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8355560
  Stats: 331 lines in 4 files changed: 313 ins; 4 del; 14 mod
  Patch: https://git.openjdk.org/valhalla/pull/1444.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1444/head:pull/1444

PR: https://git.openjdk.org/valhalla/pull/1444