Change constructor for Int to 'multi method'

src/core/Int.pm

@@ -17,7 +17,7 @@ my class Int does Real { # declared in BOOTSTRAP
             ObjAt
         );
     }
-    method new($value) {
+    multi method new($value) {
         nqp::box_i($value, self.WHAT);
     }
     multi method perl(Int:D:) {