Pass RC parameters on stream copy to the muxer.

Originally committed as revision 25384 to svn://svn.ffmpeg.org/ffmpeg/trunk

ffmpeg.c

@@ -2197,6 +2197,8 @@ static int transcode(AVFormatContext **output_files,
             }
 
             codec->bit_rate = icodec->bit_rate;
+            codec->rc_max_rate    = icodec->rc_max_rate;
+            codec->rc_buffer_size = icodec->rc_buffer_size;
             codec->extradata= av_mallocz(extra_size);
             if (!codec->extradata)
                 goto fail;