Fixed the old chap.c so that it works with the new auth.c, since

Fixed the old chap.c so that it works with the new auth.c, since
existing makefiles still refer to chap.c for all but Linux.
Fixed unsolicited Configure-Nak handling in *_nakci -- usenet report
that 'while' loop terminates too early if there's a boolean.
Fixed tiny typo in chap-new.c comment.