anchor.diff:  
   (defcfun ("if_nametoindex" %if-nametoindex)
       (errno-wrapper :unsigned-int :error-predicate zerop
  -                   :error-generator (lambda (r)
  -                                      (declare (ignore r))
  +                   :error-generator (lambda (r o)
  +                                      (declare (ignore r o))
                                         (nix::posix-error :enxio)))
     (ifname :string))
   
  
positive.code: 
  ;;; SOCKET is emulated in winsock.lisp.
  (define-socket-creation-call ("socket" %socket) :int
    "Create a BSD socket."
    (domain   :int)  ; af-*
    (type     :int)  ; sock-*
    (protocol :int))
  
negative.code:   (addrlen :pointer))
  
  (define-socket-call ("getsockopt" %getsockopt) :int
    (socket  fd)
    (level   :int)
    (optname :int)
  