RFR: 8267185: Add string deduplication support to ParallelGC

[Ivan Walulya]

Hi all,

Please review this change to add string deduplication support to ParallelGC.

Testing: All string deduplication tests, and Tier 1-5.

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Commit messages:
 - 8267185: Add string deduplication support to ParallelGC

Changes: https://git.openjdk.java.net/jdk/pull/5085/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5085&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8267185
  Stats: 219 lines in 18 files changed: 218 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5085.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5085/head:pull/5085

PR: https://git.openjdk.java.net/jdk/pull/5085