Add a comment and make them depend on libX11_xcb instead of just libX11.
The libraries which do not actually use the connection but just call APIs
are left alone.
Preparation for BeXlib (which is a ways off, but this will allow me
to build things in HaikuPorts against it properly.)
x86_64 is used as a baseline: the "x86_64" entry, whatever status it has,
is transformed into "all", and then the other entries in ARCHITECTURES
either dropped or rearranged appropriately.
