* fhandler.h (class dev_console): Add `metabit' indicating the

	* fhandler.h (class dev_console): Add `metabit' indicating the
	current meta key mode.
	* fhandler_console.cc (fhandler_console::read): Set the top bit of
	the character if metabit is true.
	* fhandler_console.cc (fhandler_console::ioctl): Implement
	KDGKBMETA and KDSKBMETA commands.
	* fhandler_tty.cc (process_ioctl): Support KDSKBMETA.
	(fhandler_tty_slave::ioctl): Send KDGKBMETA and KDSKBMETA to the
	master.
	* include/cygwin/kd.h: New file for the meta key mode.
	* include/sys/kd.h: New file.