Remove the OpenBSD and NetBSD repositories. Both project have their
own CVSweb so there is not really any big reason for us to have CVSweb
for them as well. [1]

Remove the "learn" CVS repository. It hasn't changed in 9 years... [1]

Remove the German and San Marino CVSweb mirrors from the list since
neither one has a hostname which resolves.

Suggested by: wosch [1]