Utils: Collapse most of porting,h

Taking the Qt 6 branches, leaving some dummies until downstream
adapted.

Change-Id: Ib9b86568d73c341c8f740ba497c3cbfab830d8a1
Reviewed-by: Eike Ziller <eike.ziller@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

src/plugins/texteditor/texteditor.cpp

@@ -8622,7 +8622,7 @@ IEditor *BaseTextEditor::duplicate()
 
 QT_BEGIN_NAMESPACE
 
-Utils::QHashValueType qHash(const QColor &color)
+size_t qHash(const QColor &color)
 {
     return color.rgba();
 }