debugger: enable forceful abort of mixed qml/cpp engine

Change-Id: I815f0bf91e8ca58c9e472f81a234834dc341f29d
Reviewed-by: Kai Koehne <kai.koehne@nokia.com>

src/plugins/debugger/qml/qmlcppengine.h

@@ -118,6 +118,7 @@ protected:
     void runEngine();
     void shutdownInferior();
     void shutdownEngine();
+    void abortDebugger();
 
     void notifyInferiorRunOk();
     void notifyInferiorSpontaneousStop();