moved tmp utility to utility folder.

Author: 5cript

…ringify/tmp_util/fundamental/eval_if.hpp utility/tmp_util/fundamental/eval_if.hppstringify/tmp_util/fundamental/eval_if.hpp renamed to utility/tmp_util/fundamental/eval_if.hpp stringify/tmp_util/fundamental/eval_if.hpp renamed to utility/tmp_util/fundamental/eval_if.hpp

@@ -0,0 +1,33 @@
+#pragma once
+
+namespace JSON
+{
+    template <typename...>
+    struct pack
+    {
+        using type = pack;
+    };
+
+    template <unsigned I, typename Pack>
+    struct pack_element
+    {
+        using type = typename pack_element <I - 1, Pack>::type;
+    };
+
+    template <typename Head, typename... Tail>
+    struct pack_element <0, pack <Head, Tail...>>
+    {
+        using type = Head;
+    };
+
+    template <typename T>
+    struct pack_front
+    {
+    };
+
+    template <typename Head, typename... Tail>
+    struct pack_front <pack <Head, Tail...>>
+    {
+        using type = Head;
+    };
+}