Currently non-native mode doesn't check the source package's control file to determine the platforms, instead just defaulting to the standard platforms that are roughly equivalent to `any`. In non-native mode we should refer to the `debian/control` file to figure out what platforms we need. As a note, the special cases of `any all` or `<arch> all` can be taken to simply mean `any` in the platforms key, since we will build those architecture-independent packages in any build (unless a package subset is declared).