Auto merge of #1332 - redox-os:redox-unix, r=gnzlbg

redox: convert to target_family unix

This is the first step to supporting https://github.com/rust-lang/rust/issues/60139.

In order to have a smooth transition, there will need to be a change made in rust at the same time, switching Redox over to the unix target family. See https://github.com/rust-lang/rust/pull/60547