anchor.diff:  (defun c2ffi-p ()
     "This is a hack to determine if c2ffi exists; it assumes if it
   doesn't exist, we will get a return code other than 0."
  -  (= 0 (nth-value 1 (external-program:run "c2ffi" '("-h")))))
  +  (= 0 (nth-value 1 (external-program:run *c2ffi-program* '("-h")))))
   
   (defun write-c2ffi-tempfile (input-file macro-file)
     "Write a header including the given input-file and the macro-file
  
positive.code:  ;; c2ffi
  
  (defvar *trace-c2ffi* nil)
  
  (defun run-check (program args &key output)
  
negative.code:          (arch (when arch (list "-A" arch)))
           (sysincludes (loop for dir in sysincludes
                              append (list "-i" dir))))
      (when (run-check *c2ffi-program* (list* include-file
                                      "-D" "null"
                                      "-M" output-h
                                      (append arch sysincludes))
                       :output *standard-output*)
        (prog1
            (run-check *c2ffi-program* (list* include-file "-o" output-spec
                                      (append arch sysincludes))
                       :output *standard-output*)
          (delete-file output-h)
  