[9fans] more factotum nitpicks

[presotto@plan9.bell-labs.com]

	It seems that there is no need to set .authid and .authdom
	in B /sys/src/cmd/auth/factotum/p9cr.c:getchal because there's nobody
	paying attention to them in authsrv.c anyway. Same goes for
	.authdom and .chal which are set in:

 	  cmd/auth/factotum/[apop|chap|p9cr].c ( function getchal )

	Nobody seems to care about them on the other end and what's more
	important I can't see any reason for auth protocols other than
	p9sk1 to have any business around Ticketreq.[authid|authdom|chal].
	There is no server which can supply those values.

	If there's some hidden reason for them to be set, please let me know.

	Thanks,
	Roman.

For authid and chal, no reason.  For authdom, I'm thinking of making one authsrv handle
multiple domains so it should continue to be set.