debugger: show name of core file in output pane.

This is a partial fix for http://bugreports.qt.nokia.com/browse/QTCREATORBUG-1574.

src/plugins/debugger/debuggerrunner.h

@@ -79,6 +79,7 @@ public:
     virtual void start();
     virtual void stop();
     virtual bool isRunning() const;
+    QString displayName() const;
 
     Q_SLOT void debuggingFinished();
     DebuggerStartParametersPtr startParameters() { return m_startParameters; }