Cygwin: console: Fix setting/unsetting xterm mode for input.

Cygwin: console: Fix setting/unsetting xterm mode for input.

- This patch fixes the issue that xterm compatible mode for input
  is not correctly set/unset in some situation such as:
   1) cat is stopped by ctrl-c.
   2) The window size is changed in less.
  In case 1), request_xterm_mode_input(true) is called in read(),
  however, cat is stopped without request_xterm_mode_input(false).
  In case 2), less uses longjmp in signal handler, therefore,
  corresponding request_xterm_mode_input(false) is not called if
  the SIGWINCH signal is sent within read(). With this patch,
  InterlockedExchange() is used instead of InterlockedIncrement/
  Decrement().