Merge h->slice_table[left_xy[0/1] ] checks, 4 cpu cycles speedup

Originally committed as revision 22086 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/h264.h

@@ -821,8 +821,7 @@ static void fill_decode_neighbors(H264Context *h, int mb_type){
     if(h->slice_table[topleft_xy ] != h->slice_num) h->topleft_type = 0;
     if(h->slice_table[top_xy     ] != h->slice_num) h->top_type     = 0;
     if(h->slice_table[topright_xy] != h->slice_num) h->topright_type= 0;
-    if(h->slice_table[left_xy[0] ] != h->slice_num) h->left_type[0] = 0;
-    if(h->slice_table[left_xy[1] ] != h->slice_num) h->left_type[1] = 0;
+    if(h->slice_table[left_xy[0] ] != h->slice_num) h->left_type[0] = h->left_type[1] = 0;
 }
 
 static void fill_decode_caches(H264Context *h, int mb_type){