Mixed debugger: Fix state warnings on exit

If the (child) engine is already in state InferiorShutdownOk
or InferiorExitOk, it will automatically proceed. No need
to call notifyInferiorIll(), which will lead to state warnings.

Change-Id: Id7501d327454095648be8c14d02520b2ed128e87
Reviewed-by: hjk <qthjk@ovi.com>

src/plugins/debugger/debuggerengine.cpp

@@ -1394,6 +1394,8 @@ void DebuggerEngine::quitDebugger()
         break;
     case EngineRunFailed:
     case DebuggerFinished:
+    case InferiorExitOk:
+    case InferiorShutdownOk:
         break;
     case InferiorSetupRequested:
         notifyInferiorSetupFailed();