- split softc size and match/attach out from cfdriver into
a new struct cfattach.
- new "attach" directive for files.*. May specify the name of
the cfattach structure, so that devices may be easily attached
to parents with different autoconfiguration semantics.
attaching, and to the devices when attaching them. #include <machine/bus.h>
to make this backward compatible with old #include requirements.
Also, clean up idempotency so that isa/eisa/pci "var.h" headers are
consistent (make them all idempotent).
cgd