Clear residues only in not coded channel. This fixes overwriting coded...

Clear residues only in not coded channel. This fixes overwriting coded residues with zeros if first channel is coded and second is not.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/wmalosslessdec.c

@@ -960,7 +960,7 @@ static int decode_subframe(WmallDecodeCtx *s)
                     use_normal_update_speed(s, i);
                 revert_cdlms(s, i, 0, subframe_len);
             } else
-                memset(s->channel_residues, 0, sizeof(s->channel_residues));
+                memset(s->channel_residues[i], 0, sizeof(s->channel_residues[i]));
     }
     if (s->do_mclms)
         revert_mclms(s, subframe_len);