1.0.19.17: DOLIST variable type on constant lists

1.0.19.17: DOLIST variable type on constant lists

 * When DOLIST list is a (LIST ...) form where every argument is a
   constant, constant-fold it during macro-expansion. (User has no
   direct access to the list itself, so this is safe.)

 * When DOLIST list ia a constant, add an extra binding,
   and annotate its type as (MEMBER ...).

   This means that the compiler knows that in

    (dolist (x (list 1 2 3)) ...)

   X is (INTEGER 1 3).

 * Also add a STYLE-WARNING for constant dotted lists in DOLIST.