staging: speakup: add send_xchar, tiocmset and input functionality for tty

[Okash Khawaja]

On Sat, Apr 29, 2017 at 03:06:04PM +0200, Samuel Thibault wrote:
 
> Thinking of it: for spk_ttyio_in_nowait(), we shouldn't print a warning
> when down_timeout returns ETIMEDOUT. So pr_warn should be guarded by
> "if (timeout)".
> 
> Also, spk_ttyio_in_nowait() should return 0 instead of 0xff on timeout,
> since that's used for synth_insert_next_index() which takes 0 as "no new
> value", not 0xff.
> 
> I know, it's converging slowly, but we need to make sure we don't change
> things, otherwise it'll bring regressions.
Sure, I understand. These are also things I should have considered
before submitting.

Thanks,
Okash