- 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.
to be passed as well as the fp frame.
FPE<->kernel glue code now builds a trapframe structure for passing in
and out of the post instruction emulation callback.
Signal delivery during FP emulation now works correctly.