Debugger: Do not immediately assume engine setup done

Instead of assuming engine setup done wait for the respective
signal coming from the debugger bridge.

Task-number: QTCREATORBUG-19666
Change-Id: I3b9daffc7f22ce2a0fde5c993760a2a5bda31310
Reviewed-by: hjk <hjk@qt.io>

src/plugins/debugger/lldb/lldbengine.cpp

@@ -292,7 +292,6 @@ void LldbEngine::setupEngine()
                                 .arg(bp.id().toString()).arg(bp.state()));
                 }
             }
-            notifyEngineSetupOk();
         } else {
             notifyEngineSetupFailed();
         }