[types] Enforce parameter types on specialization

[megane]

Currently no enforcing happens if specialization takes place.

Here's a case from scrutiny-tests.
Note that scheme#+ has a specialization for parameters (* *).
When using -A flag no specialization takes place, so the enforcing happens.

In this example you'd like to have the type for x to be enforced to number after the if.

;; noreturn conditional branch enforces "number" on x
(define (foo2 x)
  (if (string? x) (error "foo") (+ x 3))
  (string-append x "abc"))

;; $ csc -O3 enforce-fail.scm
;;
;; Warning: in toplevel procedure `foo2':
;;   (enforce-fail.scm:7) in procedure call to `scheme#string-append', expected argument #1 of type `string' but was given an argument of type `(not string)'

;; $ csc -A enforce-fail.scm
;;
;; Warning: in toplevel procedure `foo2':
;;   (enforce-fail.scm:7) in procedure call to `scheme#string-append', expected argument #1 of type `string' but was given an argument of type `number'