Use asm! now that rust-lang/rust#72965 is fixed?

[ssokolow]

You mention in #23 that...

I changed it to use llvm_asm! (unfortunately, the new asm! cannot be used due to rust-lang/rust#72965) and released 0.2.4, could you check if it it works for you, and if it does, close this issue?

With asm! stabilized since 1.59 and rust-lang/rust#72965 listed as fixed by rust-lang/rust#73230, would it now be feasible to use asm! and make the inline assembly option available on stable compilers?

It'd be nice to have something without the "nightly or cc or not recommended" choice to recommend to people who come in off the "actually I can’t find a simple safe way to zero memory in Rust" in https://wiki.alopex.li/LetsBeRealAboutDependencies