MER: Revert "Remove unused private api"

This reverts commit 164a301.

Still needed for old QtDeclarative.

src/corelib/kernel/qmetatype.h

@@ -743,6 +743,18 @@ ConverterFunctor<From, To, UnaryFunction>::~ConverterFunctor()
 namespace QtMetaTypePrivate {
 template <typename T, bool Accepted = true>
 struct QMetaTypeFunctionHelper {
+    static void Delete(void *t)
+    {
+        delete static_cast<T*>(t);
+    }
+
+    static void *Create(const void *t)
+    {
+        if (t)
+            return new T(*static_cast<const T*>(t));
+        return new T();
+    }
+
     static void Destruct(void *t)
     {
         Q_UNUSED(t) // Silence MSVC that warns for POD types.
@@ -770,6 +782,8 @@ struct QMetaTypeFunctionHelper {
 
 template <typename T>
 struct QMetaTypeFunctionHelper<T, /* Accepted */ false> {
+    static void Delete(void *) {}
+    static void *Create(const void *) { return 0; }
     static void Destruct(void *) {}
     static void *Construct(void *, const void *) { return 0; }
 #ifndef QT_NO_DATASTREAM