Disable undo in application output pane

The undo stack was growing endlessly, even if the size of the
output pane is limited.

Task-number: QTCREATORBUG-8402
Change-Id: I605166f691945b66cbb11f1eaa3f6729df6f6d16
Reviewed-by: hjk <qthjk@ovi.com>

src/plugins/coreplugin/outputwindow.cpp

@@ -59,6 +59,7 @@ OutputWindow::OutputWindow(Core::Context context, QWidget *parent)
     //setCenterOnScroll(false);
     setFrameShape(QFrame::NoFrame);
     setMouseTracking(true);
+    setUndoRedoEnabled(false);
 
     m_outputWindowContext = new Core::IContext;
     m_outputWindowContext->setContext(context);