RFR: 8374692: ZGC: Convert zRemembered to use Atomic<T>

[Thomas Schatzl]

On Fri, 16 Jan 2026 09:04:38 GMT, Axel Boldt-Christmas <aboldtch at openjdk.org> wrote:

> Convert usages of AtomicAccess to Atomic<T> in zRemembered.
> 
> Testing:
>  * GHA
>  * HotSpot GC tests with ZGC linux x64 and linux aarch64

Lgtm. Maybe use `compare_set` in the one case Stefan mentioned.

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Marked as reviewed by tschatzl (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/29269#pullrequestreview-3686374687