Function check_permitted_dependencies 

fn check_permitted_dependencies(
    metadata: &Metadata,
    descr: &str,
    permitted_dependencies: &[&'static str],
    restricted_dependency_crates: &[&'static str],
    permitted_location: ListLocation,
    check: &mut RunningCheck,
)

Checks the dependency of restricted_dependency_crates at the given path. Changes bad to true if a check failed.

Specifically, this checks that the dependencies are on the permitted_dependencies.