[DSOUND] fix memory leak in mixer code

[Mike Hearn]

On Sat, 22 Jan 2005 14:46:04 -0500, Robert Reif wrote:
> +	if (This->tmp_buffer)
> +	    HeapFree(GetProcessHeap(),0,This->tmp_buffer);

There's no need for the test here, it's duplicated inside HeapFree. There
was a janitorial task to clean this up not that long ago.

thanks -mike