using [paths= "crates"] will lead to sys crates installing lib in the wrong location

[Marc Trey]

step to reproduce

1 . create a project using https://github.com/RustAudio/rust-portaudio use dingy to cross compile the project , compile and check there is no build failures
2 . add in the project .cargo/config a local checkout override for rust-portaudio [paths= "../rust-portaudio"] , compile and check there is a build failure caused by libportaudio not found