change isdn4k-utils to optional

[Alan Cox]

On Tue, Sep 16, 2008 at 11:39:00PM +0200, Jos Vos wrote:
> > massive success in Germany compared to pretty much anywhere else.

It was - for various timing reaosns
 
> I'm surprised that people make so many assumptions about other countries.
> And till I do not understand why it is so unbelievable that there are
> still ISDN dialups.
> 
> B.t.w. in the Netherlands the use of ISDN has also been pretty popular
> and I know that there are still new ISDN lines delivered.

In the UK it i fairly unusual for internet service but still found in some
areas out of ADSL reach and still sold, so it hasn't gone away entirely.