Try to solve the problem of spurious EOF chars in long lines of text

Try to solve the problem of spurious EOF chars in long lines of text
sent to interactive subprocesses.
* sysdep.c (child_setup_tty): Do not enable ICANON any more.
(system_process_attributes): Remove unused var `ttotal'.
* process.c (send_process): Don't bother breaking long line with EOF
chars when talking to ttys any more.
(wait_reading_process_output): Output a warning when called in such
a way that it could block without being interruptible.