Fixed fd leak for webp coder (patch from #382)
static int WebPEncodeWriter(const unsigned char *stream,size_t length,
  const WebPPicture *const picture)
{
  Image
    *image;

  image=(Image *) picture->custom_ptr;
  return(length != 0 ? (int) WriteBlob(image,length,stream) : 1);
}

static int WebPEncodeWriter(const unsigned char *stream,size_t length,
  const WebPPicture *const picture)
{
  Image
    *image;

  image=(Image *) picture->custom_ptr;
  return(length != 0 ? (int) WriteBlob(image,length,stream) : 1);
}
