RFR: 8287734: Shenandoah: Consolidate marking closures

[Aleksey Shipilev]

On Thu, 2 Jun 2022 17:29:04 GMT, Zhengyu Gu <zgu at openjdk.org> wrote:

> Shenandoah used to have different marking closures that mark metadata or not. With Loom, marking closures always mark metadata, so they can be consolidated.
> 
> Test:
> 
> - [x] hotspot_gc_shenandoah
> - [x] jdk_loom + ShenandoahGC
> - [x] hotspot_loom + ShenandoahGC

Nice, looks good.

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Marked as reviewed by shade (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/9000