[PATCH] Rework the do_list_voices function, and fix a memory leak.

[Andrei Kholodnyi]

> That's a whole new can of worms.
> I wrote a series of patches for OpenTTS, so that it used glib's
> allocation functions wherever possible.
> In my opinion, those should be imported into Speech Dispatcher.

William,
I'd agree with Chris, since this line is just a copy/paste from above.
If Chris is ok with my modification, I'll push this patch as well.

Andrei.