[Request] OpenRC Support

Although fprintd has always "required" systemd to function, disabling checks for it has allowed fprintd to function on systems running OpenRC instead. Since the d70f15b5 commit switching to sd-bus this has no longer been possible. (On Gentoo at least, there is no way to isolate sd-bus into libsystemd and run without full systemd.)

I'd like to request support for OpenRC if that is in any way possible.