derived function types stupid about self-calls

[Nikodemus Siivola]

(defun foo (x)
  (foo x))

(defun foo (x y)
  (foo x y))

(defun foo (x)
  (foo x x))

Compiling these definitions in a row (C-c C-c in Slime) causes the second one to complain:

; caught STYLE-WARNING:
; The function was called with two arguments, but wants exactly one.

Even worse, the third one doesn't complain!

The signature checking logic should special-case self-calls.

[Nikodemus Siivola (nikodemus)]

In 1.0.43.50.