RFR: 8375093: Convert GlobalCounter to use Atomic<T>

[David Holmes]

On Thu, 15 Jan 2026 19:46:39 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

> Please review this change to make GlobalCounter use Atomic instead of
> AtomicAccess.
> 
> Testing: mach5 tier1

This all seems fine. Thanks.

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Marked as reviewed by dholmes (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/29256#pullrequestreview-3668795526