RFR: 8377045: Shenandoah: Convert ShenandoahLock related code to use Atomic<T>

[duke]

On Tue, 10 Feb 2026 17:59:56 GMT, Ben Taylor <btaylor at openjdk.org> wrote:

> Modernizes ShenandoahLock code by replacing AtomicAccess methods with Atomic types.
> 
> Tier1 test results on x86_64 linux are the same before and after this change when running with TEST_VM_OPTS=-XX:+UseShenandoahGC.

@benty-amzn 
Your change (at version cee8a7ede8d93df45589522083c7438c2a6cd21b) is now ready to be sponsored by a Committer.

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PR Comment: https://git.openjdk.org/jdk/pull/29658#issuecomment-3885240231