RFR: 8267185: Add string deduplication support to ParallelGC [v6]

[Ivan Walulya]

> Hi all,
> 
> Please review this change to add string deduplication support to ParallelGC.
> 
> Testing: All string deduplication tests, and Tier 1-5.

Ivan Walulya has updated the pull request incrementally with one additional commit since the last revision:

  more clean up

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/5085/files
  - new: https://git.openjdk.java.net/jdk/pull/5085/files/bc1cca97..2f2a2cde

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5085&range=05
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5085&range=04-05

  Stats: 52 lines in 3 files changed: 8 ins; 38 del; 6 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