Use `Requires(meta): (rpm-plugin-selinux if rpm-libs)`
    
    We support two ways to update the operating system:
    
    - `/usr/bin/rpm` (and `dnf` etc.) where SELinux labels are
      computed and written client side
    - ostree (and other image-based systems) where SELinux labels
      were computed server side.
    
    In the ostree case, I'd like the ability to generate smaller
    images that do not even have `rpm` installed.
    
    This hard dependency from `selinux-policy` -> `rpm` is one of
    the only main blockers.
    
    RPM supports these "alternative" conditionals, it's easy to do.