Debugger: Fix compilation for Qt4

Change-Id: Ibbde1aab3af5e5948ba2982ad795dae7ac38f509
Reviewed-by: hjk <hjk121@nokiamail.com>

src/plugins/debugger/debuggerplugin.cpp

@@ -2641,7 +2641,9 @@ QMessageBox *showMessageBox(int icon, const QString &title,
         title, text, QMessageBox::StandardButtons(buttons),
         ICore::mainWindow());
     mb->setAttribute(Qt::WA_DeleteOnClose);
+#if (QT_VERSION >= QT_VERSION_CHECK(5, 0, 0))
     mb->setTextInteractionFlags(Qt::TextSelectableByMouse);
+#endif
     mb->show();
     return mb;
 }