- Adds a `crate_type` kwarg to library targets, allowing the different
types of Rust [linkage][1].
- Shared libraries use the `dylib` crate type by default, but can also
be `cdylib`
- Static libraries use the `rlib` crate type by default, but can also
be `staticlib`
- If any Rust target has shared library dependencies, add the
appropriate linker arguments, including rpath for the sysroot of the
Rust compiler
[1]: https://doc.rust-lang.org/reference/linkage.html