RunControl: Make icon(path) a value member

Change-Id: I7f7099d03a25a14d8df02273cca928e9f1fbfe1d
Reviewed-by: Eike Ziller <eike.ziller@digia.com>

src/plugins/debugger/debuggerrunner.h

@@ -64,7 +64,6 @@ public:
     StopResult stop(); // Called from SnapshotWindow.
     bool isRunning() const;
     QString displayName() const;
-    QIcon icon() const;
 
     void startFailed();
     void debuggingFinished();