ProjectExplorer: Allow text filtering in message pane

Change-Id: I7b70f7056c757fcb13634021b8e2dcf0b3a34097
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/coreplugin/messageoutputwindow.h

@@ -64,6 +64,8 @@ public:
     bool canNavigate() const override;
 
 private:
+    void updateFilter() override;
+
     OutputWindow *m_widget;
 };