* Make S expand to an absolute path at compile time.
* Use `-S' rather than `-x' to remove debugging symbols.
* Garbage collect unused variables.
* Reverse a handful of port-specific changes that do not correspond to
the common build model and are not needed.
- 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.