Fix lupdate issues

When updating translations with
cmake --build . --target ts_de
(or other language ID)

- Qualifying with unknown namespace/class ::PluginSpecPrivate
- <class> lacks Q_OBJECT macro

Change-Id: Ic42d8dffea935e6b10e59223bdedb9a8a4dcf446
Reviewed-by: hjk <hjk@qt.io>

src/plugins/clangcodemodel/clangdclient.cpp

@@ -4021,7 +4021,7 @@ class MemoryTreeModel : public Utils::BaseTreeModel
 public:
     MemoryTreeModel(QObject *parent) : BaseTreeModel(parent)
     {
-        setHeader({tr("Component"), tr("Total Memory")});
+        setHeader({MemoryUsageWidget::tr("Component"), MemoryUsageWidget::tr("Total Memory")});
     }
 
     void update(const MemoryTree &tree)