Add GNU/Hurd support

[sthibaul]

No description provided.

[sunfishcode]

Thanks! This looks good; could you also add a cargo check -Z build-std --target=i686-unknown-hurd-gnu --features=all-apis line to the "Check selected Tier 3 platforms" section in .github/workflows/main.yml script, so that we avoid breaking GNU/Hurd support in the future?

[sthibaul]

Yes, that'll just have to wait for rust-lang/libc#3325 to land

[sunfishcode]

Ah, I didn't realize we were at that early stage of the process. My sense then is that we can merge this now, and add the CI check later once it's ready.

[sthibaul]

Thanks, I have created the backport PR #852 for rustc bootstrap

[sunfishcode]

This is now released in rustix 0.38.15.

[sthibaul]

Thanks!