Add support for GNU/Hurd #53

	name: CI
	on: [push, pull_request]

	env:
	CARGO_TERM_COLOR: always

	jobs:
	test:
	name: cargo test
	runs-on: ${{ matrix.os }}
	strategy:
	matrix:
	os: [ubuntu-latest, macos-latest, windows-latest]
	rust: [1.21.0, stable]
	include:
	- os: ubuntu-latest
	rust: nightly
	- os: windows-latest
	rust: stable-i686
	- os: windows-latest
	rust: stable-x86_64-gnu
	exclude:
	# rust/libc does not appear to link on macos-latest with rust 1.21.0
	- os: macos-latest
	rust: 1.21.0
	steps:
	- name: Checkout sources
	uses: actions/checkout@v3

	- name: Install toolchain
	uses: dtolnay/rust-toolchain@master
	with:
	toolchain: ${{ matrix.rust }}

	- name: Generate lock file
	run: cargo generate-lockfile

	# cfg-if 0.1.10 does not support rust 1.21.0, so downgrade it to the last
	# known working version after generating the lockfile above
	- name: Downgrade dependencies
	if: matrix.rust == '1.21.0'
	run: cargo update -p cfg-if --precise 0.1.9

	- name: Run `cargo check`
	run: cargo check

	- name: Run `cargo test`
	run: cargo check

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