RunControl: Show correct icon in application output

Add a virtual icon() method to runcontrol.
Actually currently the icon only varies between modes of running.

Task-Nr: QTCREATORBUG-1232

src/plugins/qmlprojectmanager/qmlprojectruncontrol.h

@@ -54,6 +54,7 @@ public:
     virtual void start();
     virtual StopResult stop();
     virtual bool isRunning() const;
+    virtual QIcon icon() const;
 
 private slots:
     void processExited(int exitCode);