Remove all vestiges of /usr programs (awk, sed, grep...) from MAKEDEV.

Remove all vestiges of /usr programs (awk, sed, grep...) from MAKEDEV.
MAKEDEV can now run (with /sbin/chown and /bin/chgrp, still) without
any /usr.  The default PATH for MAKEDEV is now "/sbin:/bin" to prevent
against further spammage of /usr programs in MAKEDEV.  In the event
of an emergency, the variable "MAKEDEVPATH" can be used to replace
PATH, but I don't know what that emergency could be.
   Let me know if you have any problems.  I've tested it as well as
I could, which basically means everything except for RocketPorts.

Reviewed in principle by:	peter