cups: Don't build on Darwin
kde-3: Remove

KDE 3 hasn't built in a long time.  Also remove six, the only package
with a dependency on KDE 3.
linux-2.6.32-xen: Remove

Hasn't built in a long time and is obsolete anyway.
openoffice: Remove

It's superseded by LibreOffice and doesn't build anymore.
Rename openoffice directory to libreoffice