Never use input_fd if using X.

Never use input_fd if using X.
(stuff_char): Do nothing if read_socket_hook.
(setpgrp_of_tty): Function deleted.
(init_sigio): Take fd as argument.  Callers changed.
Don't call request_sigio; do the work here.
(request_sigio, unrequest_sigio): Do nothing if read_socket_hook.
(init_sys_modes): Don't call EMACS_GET_TTY unless we are going
to change the settings.