simplify ff_h263_round_chroma()

Originally committed as revision 9602 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/mpegvideo.h

@@ -765,14 +765,9 @@ static inline int get_bits_diff(MpegEncContext *s){
 static inline int ff_h263_round_chroma(int x){
     static const uint8_t h263_chroma_roundtab[16] = {
     //  0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15
-        0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2,
+        0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1,
     };
-    if (x >= 0)
-        return  (h263_chroma_roundtab[x & 0xf] + ((x >> 3) & ~1));
-    else {
-        x = -x;
-        return -(h263_chroma_roundtab[x & 0xf] + ((x >> 3) & ~1));
-    }
+    return h263_chroma_roundtab[x & 0xf] + (x >> 3);
 }
 
 /* motion_est.c */