AArch64 SIMD intrinsics are now stable

[Shnatsel]

rust-lang/stdarch#1266 has landed and shipped in v1.59

Note that documentation still displays the intrinsics as unstable due to a rustdoc bug: rust-lang/stdarch#1268

It should be possible to remove the feature gate now and enable SIMD on ARM by default.

[hkratz]

Thanks for the heads-up. Will look into it.

[marmeladema]

One thing to note though is that the neon target feature on which those intrinsics depend have not been stabilized yet but will be in 1.61

[hkratz]

Fixed in v0.1.4. For Rust 1.59 and 1.60 the aarch64_neon feature is still required for the aarch64 SIMD implementation. For Rust 1.61 the aarch64 SIMD implementation is enabled automatically with availability of target_feature = "neon".