Remove ftp.uu.net from gnu fetch group

[Ryan Schmidt]

The readline port uses the gnu fetch group to download.

ftp://ftp.uu.net/archive/systems/gnu/ is in that group.

But ftp://ftp.uu.net/archive/systems/gnu/readline/ doesn't appear to  
have any current readline files.

All modifications dates on that server seem to be 2001-06-29. If the  
mirror hasn't been updated since then, we should remove it from the  
list of gnu mirrors.

Comments?