RFR: 8258508: Merge G1RedirtyCardsQueue into qset

[Kim Barrett]

Please review this change to G1RedirtyCardsLocalQueueSet to directly
incorporate the associated queue, simplifying usage.

Testing:
mach5 tier1

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Commit messages:
 - merge redirty cards queue into local qset

Changes: https://git.openjdk.java.net/jdk/pull/2325/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2325&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8258508
  Stats: 55 lines in 5 files changed: 12 ins; 26 del; 17 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2325.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2325/head:pull/2325

PR: https://git.openjdk.java.net/jdk/pull/2325