Fix building with C++11
Fix building with C++11

DrTobe/libqtxdg,DrTobe/libqtxdg,libqtxdg/libqtxdg,libqtxdg/libqtxdg,DrTobe/libqtxdg,gilir/libqtxdg-qt5,lxde/libqtxdg,gilir/libqtxdg-qt5,luis-pereira/libqtxdg,lxde/libqtxdg,luis-pereira/libqtxdg