Pull up following revision(s) (requested by jmcneill in ticket #848):
	xsrc/external/mit/xf86-input-keyboard/dist/src/bsd_kbd.c: revision 1.18
	sys/dev/wscons/wsmux.c: revision 1.55
If there are no devices attached to the mux and software does
WSxxxIO_SETVERSION, the change doesn't actually get applied to the event
source as wsmux hands off processing of these ioctls to attached devices.
Handle these ioctls directly from the mux device instead of passing them
through, to correct an issue that prevented keyboards and mice from working
in X if there were zero devices attached when the X server started.
If WSKBDIO_GTYPE succeeds and returns type=0, it is a mux with no keyboard
attached. In this case, assume USB.