Prefix Tr::tr contexts with ::

To make outliers better visible in Linguist

Change-Id: Ic35ea2a858b7e3576d9a416fb494fddb616eaaa1
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/clangcodemodel/clangdmemoryusagewidget.h

@@ -11,7 +11,7 @@ class ClangdClient;
 
 class ClangdMemoryUsageWidget : public QWidget
 {
-    Q_DECLARE_TR_FUNCTIONS(ClangCodeModel)
+    Q_DECLARE_TR_FUNCTIONS(::ClangCodeModel)
 public:
     explicit ClangdMemoryUsageWidget(ClangdClient *client);
     ~ClangdMemoryUsageWidget();