revert r11677, it is considered speed critical

Originally committed as revision 11688 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/h263.c

@@ -4727,7 +4727,7 @@ static inline int mpeg4_decode_block(MpegEncContext * s, DCTELEM * block,
                               int n, int coded, int intra, int rvlc)
 {
     int level, i, last, run;
-    int dc_pred_dir = 0;
+    int dc_pred_dir;
     RLTable * rl;
     RL_VLC_ELEM * rl_vlc;
     const uint8_t * scan_table;