Declare _rl_redisplay_after_sigwinch.
[__DJGPP__]: Don't declare term_buffer and term_string_buffer (they are
unused.)
(_rl_get_screen_size) [__DJGPP__]: Call ScreenRows and ScreenCols.
(_rl_init_terminal_io) [__GO32__]: Don't call them here. Instead, call
_rl_get_screen_size. Set terminal_name. Return 0, to be consistent with
the function's declaration.
(ding) [__GO32__]: Support visual bell by calling ScreenVisualBell.
