`k` template modifier in x86

[amosonn]

I don't know if this is the place for such comments, but:
What is the reason for using k as the modifier for getting the 32-bit version of the register (i.e. eax), instead of the common d (for dword)? This matches using w for the word and q for the qword versions.

[Amanieu]

The latest version of the RFC is at rust-lang/rfcs#2850. The one in this repo is out of date. I have changed the modifiers to make them more consistent in the updated RFC.

[amosonn]

Cool, thanks!