So far we had %cargo_install (for binaries) and %cargo_install_crate
(for libraries) which is a bit awkward and requires us to put
additional arguments for latter one.
We can do all the magic behind the scene.
Closes: https://pagure.io/fedora-rust/rust2rpm/issue/7
Signed-off-by: Igor Gnatenko <ignatenkobrain@fedoraproject.org>
