Does not build on aarch64-pc-windows-msvc

[RalfJung]

aarch64-pc-windows-msvc is on track to becoming a tier 1 target soon (rust-lang/rfcs#3817). However, this crate does not build on aarch64-pc-windows-msvc because it depends on winapi, which doesn't support aarch64 (and, given its maintenance status, it is unlikely that it ever will).

Probably the best way to fix this is to use windows-sys / windows-rs instead of winapi. Unfortunately I am not a Windows person so I know next to nothing about what this would take. :)

(This came up in rust-lang/miri#4479)

[dpaoliello]

Winapi 0.3.7 supports Arm64 Windows, and this project specifies winapi 0.3. Is there actually an issue building this crate?

[RalfJung]

Ah, I didn't pay close attention to the exact versions of winapi that show up in the dependencies of rustup-toolchain-install-master, so I missed the fact that there's 0.2 and 0.3 in play here. Sorry for the confusion!