mpegvideo: dont use ff_mspel_motion() for vc1

Fixes Ticket655
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/mpegvideo_common.h

@@ -725,7 +725,7 @@ static av_always_inline void MPV_motion_internal(MpegEncContext *s,
                         0, 0, 0,
                         ref_picture, pix_op, qpix_op,
                         s->mv[dir][0][0], s->mv[dir][0][1], 16);
-        }else if(!is_mpeg12 && (CONFIG_WMV2_DECODER || CONFIG_WMV2_ENCODER) && s->mspel){
+        }else if(!is_mpeg12 && (CONFIG_WMV2_DECODER || CONFIG_WMV2_ENCODER) && s->mspel && s->codec_id == CODEC_ID_WMV2){
             ff_mspel_motion(s, dest_y, dest_cb, dest_cr,
                         ref_picture, pix_op,
                         s->mv[dir][0][0], s->mv[dir][0][1], 16);