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/extensionsystem/pluginspec.cpp

@@ -156,7 +156,7 @@ namespace ExtensionSystem {
     \fn uint ExtensionSystem::qHash(const ExtensionSystem::PluginDependency &value)
     \internal
 */
-Utils::QHashValueType qHash(const PluginDependency &value)
+size_t qHash(const PluginDependency &value)
 {
     return qHash(value.name);
 }