Enable x86 F16C hardware intrinsics on stable Rust

[VoidStarKat]

F16C hardware intrinsics still not stabilized, just needs stabilization PR rust-lang/stdarch#1234

Probably the biggest priority for crate now that const conversions are done.

[VoidStarKat]

Opened PRs for stabilization: rust-lang/stdarch#1366 and rust-lang/rust#106323

[mert-kurttutan]

@starkat99 just wanted to see if you have any non-public update on this one. F16C intrinsic (when using rust nightly) provides performance improvements for my project.

[mert-kurttutan]

Seems like your PR is merged. Any plan to release a new version for this feature ?

[Shnatsel]

The necessary intrinsics have shipped on stable in 1.70.0