[mythtv] audio write() error check

[Bruce Markey]

manu wrote:
> You got my point. Sorry I did not explain my patch when sending it, I  
> thought it was trivial.
> The idea was just that the test was always false and the useless and  
> also that errors will never be caught.

Right, so I had it essentially backwards but the original code
was just so unfamiliar and awkward. That's probably why the
logic was horked in the first place. What I'd expect to see >99%
of the time would be:

   while (written < size)
   {
       lw = write(audiofd, tmpbuf, size - written);

       if (lw == -1)
       {
           cerr << "Error writing to audio device, exiting\n";
           close(audiofd);
           audiofd = -1;
           return;
       }
       written += lw;
       tmpbuf += lw;
   }

The write doesn't happen when written reaches size either way
so there was no need to put the write inside the while statement.

--  bjm