over-strong warnings about DECLARE in walker

[Christophe Rhodes]

 affects sbcl
 status confirmed
 importance low
 tag walker declare
 done

The walker is overly confident that misplaced DECLAREs are definitely
wrong:

    (defmethod foo ()
      (flet ((declare (x) (print x)))
        (progn (declare 3))))

is perfectly legal and should compile with at most STYLE-WARNINGs, but
generates a full WARNING. (The equivalent DEFUN generates no warnings
at all, and we should be consistent between DEFUN and DEFMETHOD).

[Christophe Rhodes (csr21-cantab)]

Arguably I'm wrong about this: CLHS DECLARE says "The consequences of trying to use a declare expression as a form to be evaluated are undefined." which might trump the idea that one can add a local function binding to CL:DECLARE.