Debugger: Avoid some undesired state transitions on shutdown

Seeing an ill engine while trying to stop means that the stop failed.
Also, a finished master engine doesn't need further updates.

Task-number: QTCREATORBUG-14089
Change-Id: Icd5b090dfcdc0875953d8756a909b1405e05f71f
Reviewed-by: Christian Stenger <christian.stenger@theqtcompany.com>

src/plugins/debugger/debuggerengine.cpp

@@ -1139,6 +1139,8 @@ void DebuggerEngine::notifyEngineIll()
             interruptInferior();
             break;
         case InferiorStopRequested:
+            notifyInferiorStopFailed();
+            break;
         case InferiorStopOk:
             showMessage(_("FORWARDING STATE TO InferiorShutdownFailed"));
             setState(InferiorShutdownFailed, true);