debugger: limit log window to 100000 lines.

src/plugins/debugger/debuggeroutputwindow.cpp

@@ -68,6 +68,7 @@ public:
     DebuggerPane(QWidget *parent)
         : QPlainTextEdit(parent)
     {
+        setMaximumBlockCount(100000);
         m_clearContentsAction = new QAction(this);
         m_clearContentsAction->setText(tr("Clear contents"));
         m_clearContentsAction->setEnabled(true);