Qt Designer plugin: Use C++ 11 member initialization.

Simplify/obsolete constructors accordingly.

Change-Id: Id7b974317f2be81a89ff3a279eed95171d34991f
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>

src/plugins/designer/resourcehandler.h

@@ -70,8 +70,8 @@ private:
 
     QDesignerFormWindowInterface * const m_form;
     QStringList m_originalUiQrcPaths;
-    bool m_initialized;
-    bool m_handlingResources;
+    bool m_initialized = false;
+    bool m_handlingResources = false;
 };
 
 } // namespace Internal