Merge branch 'grubba/pty-handling' into 8.0

* grubba/pty-handling:
  I/O [NT]: Fixed typo.
  Stdio [NT]: Fixed compilation error when no struct termios.
  Diagnostics [NT]: Fixed multiple issues with FD_DEBUG.
  I/O [NT]: Enable some termios functions on NT.
  I/O [NT]: Implemented TIOCGWINSZ and TIOCSWINSZ ioctls.
  I/O: Make termios code dependent on presence of tcgetattr().
  Stdio: Fix get_all_args() call to support Pike 8.0 and earlier.
  Stdio.File: Added tcdrain() and tcsetsize().