Taken from X11, weston and consolekit2 ports for FreeBSD.
Setting just K_CODE as done before makes input seemingly have no ill
effects, but it is still buffered and possibly send to the terminal
after application exit if stdin is never drained. Setting raw mode
appears to be needed to solve that issue.
A K_OFF-like VT keyboard setting like Linux has would seem more
appropriate, but that is not currently available to us on FreeBSD.
The VT and KD ioctl's are picky about the tty fd used. In order to
satisfy these, and to improve state cleanup, we now only and store the
current tty when opening a client, and use this fd to perform teardown
later. The presence of the fd is also used to signal that teardown is
needed.
