tty_debug_hangup
# define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args)
# define tty_debug_hangup(tty, f, args...) do {} while (0)
# define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args)
# define tty_debug_hangup(tty, f, args...) do { } while (0)