Recent changes in Nixpkgs makes it more strict.
This is a change that wasn't caught as needed from the migration to
structured options for device infos.
Instead of the following error message:
```
error: The option `mobile.device.info' defined in `<unknown-file>' does not exist.
(use '--show-trace' to show detailed location information)
```
We now get:
```
error: The option `mobile.device.info' defined in `.../mobile-nixos/devices/asus-z00t' does not exist.
(use '--show-trace' to show detailed location information)
```
We are now splitting the concerns more clearly, by making `baseModules`
the reason we are evaluating NixOS, rather than wholesale always
including it into the modules.