Rollup merge of #112150 - taiki-e:apple-atomic-128, r=Amanieu

Support 128-bit atomics on all x86_64 Apple targets

On x86_64, we currently set `max_atomic_width` to 128 only on macOS.

https://github.com/rust-lang/rust/blob/ad8304a0d5280de30856b39c19df7b306957e878/compiler/rustc_target/src/spec/x86_64_apple_darwin.rs#L8

However, other x86_64 Apple targets (iOS, tvOS, and watchOS) are also core2+ and support cmpxchg16b.

https://github.com/rust-lang/rust/blob/ad8304a0d5280de30856b39c19df7b306957e878/compiler/rustc_target/src/spec/apple_base.rs#L71-L76

```console
# Script to get targets that support cmpxchg16b by default:
$ (for target in $(rustc --print target-list); do [[ $target == "x86_64"* ]] && rustc --print cfg --target "$target" | grep -q cmpxchg16b && echo "$target"; done)
x86_64-apple-darwin
x86_64-apple-ios
x86_64-apple-ios-macabi
x86_64-apple-tvos
x86_64-apple-watchos-sim
x86_64h-apple-darwin
```

r? `@Amanieu`

Author: compiler-errors