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/libs/cplusplus/LookupItem.h

@@ -71,6 +71,6 @@ private:
     ClassOrNamespace *_binding;
 };
 
-Utils::QHashValueType qHash(const CPlusPlus::LookupItem &result);
+size_t qHash(const CPlusPlus::LookupItem &result);
 
 } // namespace CPlusPlus