Check transform==15 first, since it's more common than 13.

Patch by Dark Shikari

Originally committed as revision 20749 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/vp3.c

@@ -1366,7 +1366,7 @@ static void reverse_dc_prediction(Vp3DecodeContext *s,
 
                     /* check for outranging on the [ul u l] and
                      * [ul u ur l] predictors */
-                    if ((transform == 13) || (transform == 15)) {
+                    if ((transform == 15) || (transform == 13)) {
                         if (FFABS(predicted_dc - vu) > 128)
                             predicted_dc = vu;
                         else if (FFABS(predicted_dc - vl) > 128)