change &c variables to default to a Callable type object

blows up in the optimizer while compiling the setting

src/Perl6/Actions.pm

@@ -153,7 +153,7 @@ class Perl6::Actions is HLL::Actions {
                     %info<bind_constraint>, [@value_type[0]], nqp::hash());
             }
             %info<value_type>     := %info<bind_constraint>;
-            %info<default_value>   := $*W.find_symbol(['Any']);
+            %info<default_value>   := $*W.find_symbol(['Callable']);
         }
         else {
             %info<container_base>     := $*W.find_symbol(['Scalar']);