Fix Q_WS_* usage for Qt5.
Qt5 doesn't define Q_WS_, instead we need to use Q_OS_ flags. This updates the code to check for Q_OS_LINUX in addition to Q_WS_X11 flags.
Qt5 doesn't define Q_WS_, instead we need to use Q_OS_ flags. This updates the code to check for Q_OS_LINUX in addition to Q_WS_X11 flags.