AC_FUNC_SEEKO is the name of the autoconf macro. HAVE_FSEEKO is the name of the C preprocessor symbol. Do not confuse the two. See xemacs-patches message <CAHCOHQ=i7N2mYiE+M7O+0jqnDtmCBPSx+iitaintGJ=Ttwcf8Q@mail.gmail.com>.

;; For our purposes we can treat the vt200 and vt100 almost alike.
;; Most differences are handled by the termcap entry.
(load "term/vt100" nil t)

;; Make F11 an escape key.
(define-key function-key-map "\e[23~" [?\e])