atomic128: use the new intrinsics::atomic_load

[teskje]

In rust-lang/rust#141507, the atomic_load_{ordering} intrinsics were gated behind the bootstrap config and replaced with a single atomic_load intrinsic. This breaks running Miri on this crate with a recent nightly version:

error[E0425]: cannot find function `atomic_load_acquire` in module `intrinsics`
   --> src/imp/atomic128/intrinsics.rs:76:36
    |
76  |             Acquire => intrinsics::atomic_load_acquire(src),
    |                                    ^^^^^^^^^^^^^^^^^^^ help: a function with a similar name exists: `atomic_and_acquire`
    |
   ::: /Users/jan/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/core/src/intrinsics/mod.rs:656:1
    |
656 | pub unsafe fn atomic_and_acquire<T: Copy>(dst: *mut T, src: T) -> T;
    | -------------------------------------------------------------------- similarly named function `atomic_and_acquire` defined here
    |
note: found an item that was configured out
   --> /Users/jan/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/core/src/intrinsics/mod.rs:437:15
    |
437 | pub unsafe fn atomic_load_acquire<T: Copy>(src: *const T) -> T;
    |               ^^^^^^^^^^^^^^^^^^^
note: the item is gated here
   --> /Users/jan/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/core/src/intrinsics/mod.rs:436:1
    |
436 | #[cfg(bootstrap)]
    | ^^^^^^^^^^^^^^^^^

[...]

This PR moves the portable-atomic crate to that new intrinsic to unbreak Miri.

[teskje]

Well, looks like just replacing isn't going to work. Is there a way to version-gate based on a nightly version?

[taiki-e]

Thanks for the PR!

From looking at the rust-lang/rust PR that made this change, it seemed they intended to change other intrinsics in the near future, so for now I plan to simply disable it in recent nightlies affected: 4420e87

[teskje]

Makes sense, thanks!

[taiki-e]

Published the fix for this issue in portable-atomic 1.11.1.