Auto merge of #8139 - mati865:patch-1, r=ehuss

Auto merge of #8139 - mati865:patch-1, r=ehuss

Add windows-gnu CI and fix tests

One remaining failure:
```
---- features::feature_off_dylib stdout ----
running `d:\a\1\s\target\debug\cargo.exe build --features f1`
running `d:\a\1\s\target\debug\cargo.exe run -p bar`
thread 'features::feature_off_dylib' panicked at '
Expected: execs
    but: exited with exit code: 101
--- stdout

--- stderr
   Compiling foo v0.0.1 (D:\a\1\s\target\cit\t663\foo)
   Compiling bar v0.0.1 (D:\a\1\s\target\cit\t663\foo\bar)
    Finished dev [unoptimized + debuginfo] target(s) in 0.69s
     Running `target\debug\bar.exe`
thread 'main' panicked at 'assertion failed: `(left == right)`
  left: `"f1"`,
 right: `"no f1"`', bar\src\main.rs:5:17
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
error: process didn't exit successfully: `target\debug\bar.exe` (exit code: 101)
', crates\cargo-test-support\src\lib.rs:833:13
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

failures:
    features::feature_off_dylib
```

I disassembled the dylibs and `cargo run -p bar` correctly rebuilt it inside `target/debug/deps/` but did not copy it to `target/debug`. To further confirm, calling `cp target/debug/deps/foo.dll target/debug/` manually solved the issue.
Any idea?

----

I left `FIXME` in places where import lib should be added with https://github.com/rust-lang/cargo/pull/6875.

`TOOLCHAIN: nightly-x86_64-pc-windows-gnu` can be replaced with beta on Thursday.