RFR: 8275051: Shenandoah: Correct ordering of requested gc cause and gc request flag

[Aleksey Shipilev]

On Mon, 11 Oct 2021 18:07:01 GMT, Zhengyu Gu <zgu at openjdk.org> wrote:

> Although setting gc request is under _gc_waiters_lock, but read side (run_service()) does not take the lock. We need to enforce following ordering, so that read side sees latest requested gc cause when the flag is set.
> 
> Test:
> - [x] hotspot_gc_shenandoah

Looks good!

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Marked as reviewed by shade (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/5898