Does not appear to follow target specified in .cargo/config

I have a project that uses Rust for a target other than the one I am building on.
In my case: an embedded target (drastically different architecture).

It seems like the CMake module does not pick up on the target set in `.cargo/config`.

Building the library on its own with just `cargo build` does, of course, apply that option, and it builds successfully as expected.
However, when I set up CMakeRust to build it, it ends up trying to build the lib for `i686-unknown-linux-gnu`.

It looks like the target is inferred in `CMakeCargo.cmake`, with no option to set it as an argument?