RFR: 8368989: Use NMethodMarkingScope and ThreadsClaimTokenScope in shenandoahSTWMark [v2]

[duke]

On Thu, 2 Oct 2025 09:31:05 GMT, Francesco Andreuzzi <fandreuzzi at openjdk.org> wrote:

>> Replace `StrongRootsScope` with `ThreadsClaimTokenScope` in `shenandoahSTWMark` to be more precise with what is needed and why. 
>> 
>> - `ShenandoahSTWMark` uses `MarkingNMethodClosure`, so we also need `NMethodMarkingScope`.
>> - `nworkers` is guaranteed to be > 0
>> 
>> Passes `tier1` and `tier2` (fastdebug).
>
> Francesco Andreuzzi has updated the pull request incrementally with one additional commit since the last revision:
> 
>   trigger

@fandreuz 
Your change (at version 0801a4965d20cf84b2e4be04c4ab4a98a5e7234c) is now ready to be sponsored by a Committer.

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PR Comment: https://git.openjdk.org/jdk/pull/27589#issuecomment-3360986058