h263 modified quantization fix

Originally committed as revision 2557 to svn://svn.ffmpeg.org/ffmpeg/trunk
diff --git a/libavcodec/msmpeg4.c b/libavcodec/msmpeg4.c
index b3f61a2..d8a8e48 100644
--- a/libavcodec/msmpeg4.c
+++ b/libavcodec/msmpeg4.c
@@ -1258,7 +1258,7 @@
     if(!had_i) return -1;
 }
 #endif
-    s->qscale = get_bits(&s->gb, 5);
+    s->chroma_qscale= s->qscale = get_bits(&s->gb, 5);
     if(s->qscale==0){
         av_log(s->avctx, AV_LOG_ERROR, "invalid qscale\n");
         return -1;