RFR: 8258142: Simplify G1RedirtyCardsQueue

[Ivan Walulya]

On Sun, 13 Dec 2020 01:45:20 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

> Please review this change to G1RedirtyCardsQueue to separate the local qset
> from the queue. This simplifies the implementation, though requires clients
> to deal with the local qset explicitly. This is an enabling step toward
> desired simplifications of the PtrQueue hierarchy. This change also
> simplifies the interaction between the local qset and the global qset.
> 
> Testing:
> mach5 tier1-5

looks good

minor:
maybe maintain the postfix `_qset ` in the naming of `_rdclqs` as done for `_shared_qset` and `_local_qset`

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Marked as reviewed by iwalulya (Committer).

PR: https://git.openjdk.java.net/jdk/pull/1755