Detect non-Rust code

[kellytk]

If this plugin is the correct project for the feature, it would be helpful to me to be able to detect the use of non-Rust code in a dependency tree.

[anderejd]

Thanks for the suggestion. Are we talking about identifying and presenting stats for FFI?

Related: #6

[kellytk]

@anderejd Anything that results in non-Rust code being executed.

[pinkforest]

@kellytk if you don't mind mind we could use a test crate that includes all sorts of code that should not be included but current cargo-geiger includes so we can have a real nice repro and include in CI :)

[kellytk]

As I now only write Rust I probably wouldn't be able to help with that unfortunately.