P3323R1 Forbid `atomic<cv T>`, Specify `atomic_ref<cv T>`

[StephanTLavavej]

WG21-P3323R1 Forbid atomic<cv T>, Specify atomic_ref<cv T>

No feature-test macro is mentioned.

Let's implement this unconditionally, per A. Jiang (@frederick-vs-ja)'s observation below.

[frederick-vs-ja]

It seems that this should be treated as a DR because it mainly resolves 2 LWG issues.