New assembly syntax

[katietheqt-old]

Our crate is currently broken on nightly because we need to update our assembly syntax or keep using legacy assembly. I will get around to this if nobody else does soon. This will break compatibility with nightlies older than a few weeks at maximum, so this will probably be a breaking change (@phil-opp please confirm this).

[phil-opp]

I don't think that anything is broken right now, the CI jobs succeeded with the latest nightly (apart from clippy): https://github.com/rust-osdev/x86_64/actions/runs/145726670 . We're using llvm_asm! instead of asm! since version 0.10.2, perhaps you're on an older version?

I'm of course open to switching to the new asm! macro anyway, so feel free to send in a PR if you like. We can publish it as a semver-breaking version to avoid breaking people on older nightlies if we want to.

[katietheqt-old]

Huh, I could have sworn I saw the latest build being broken because of this when I posted it. My bad. Regardless, moving to the new asm! macro would be great