improving config.hpp, renaming any_arg to template_worm

example/is_constexpr_function_object.cpp

@@ -4,9 +4,8 @@ Distributed under the Boost Software License, Version 1.0.
 (See accompanying file LICENSE.md or copy at http ://boost.org/LICENSE_1_0.txt)
 ->*/
 
-#include <callable_traits/is_constexpr.hpp>
-#ifdef CALLABLE_TRAITS_MSVC
-//feature is unsupported in MSVC
+#include <callable_traits/config.hpp>
+#ifdef CALLABLE_TRAITS_DISABLE_CONSTEXPR_CHECKS
 int main(){ return 0; };
 #else