for hb devices.
- Move declarations for hb functions and macros to dev/hbvar.h.
- Define and use hb_badaddr() macro for hb devices.
- Declare news3400_badaddr() in machine/cpu.h rather than machine/autoconf.h.
- Remove unused stuff from machine/autoconf.h.
indicating an unhandled "command". ERESTART is -1, which can lead to
confusion. ERESTART has been moved to -3 and EPASSTHROUGH has been
placed at -4. No ioctl code should now return -1 anywhere. The
ioctl() system call is now properly restartable.