change isdn4k-utils to optional

[Benny Amorsen]

Ralf Ertzinger <fedora at camperquake.de> writes:

> There are (and always will be, I suspect) places where anything faster
> than ISDN will simply not be available.

Do you know anyone who uses dialup ISDN?

Generally people around here who use dialup use it on their cell
phones (which is fairly hard to set up in Fedora, by the way). There
are still a few users on analog dialup too. But ISDN? No way.


/Benny