deprecate some linux ports

[Alexander Best]

seems like a good idea. especially for people new to freebsd the different
linux base versions are confusing.

the only linux-f8-* port i'm running atm is graphics/linux-f8-libGLU since
there's no linux-f10-libGLU port available. using graphics/linux-f10-dri
instead isn't an option for me since the port shares some files with the
nvidia freebsd binary graphic drivers.

cheers.
alex