libavcodec/wmalosslessdec: add missing emms

prevent failure with mmx2
should fix fate failure on freebsd mmx2 client

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

libavcodec/wmalosslessdec.c

@@ -798,6 +798,7 @@ static void revert_cdlms(WmallDecodeCtx *s, int ch,
             s->channel_residues[ch][icoef] = input;
         }
     }
+    emms_c();
 }
 
 static void revert_inter_ch_decorr(WmallDecodeCtx *s, int tile_size)