New versions of Xorg server & tools are defaulting to using "base" instead
of "xorg" for the XKB rules now, since that is the preferred name established
by the xkb-config project. While we can patch each one in the Sun builds,
this is more work and won't help users who build their own, or copy config files
from other systems, so we should just add the base rules file/link in our packages
as well.