Fix a warning by removing an useless assignment (buf_ptr should be only

used in the RTP muxer, and not in the demuxer)

Originally committed as revision 10561 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/rtp.c

@@ -690,7 +690,6 @@ int rtp_parse_packet(RTPDemuxContext *s, AVPacket *pkt,
                 len -= infos->au_headers[0].size;
             }
             s->read_buf_size = len;
-            s->buf_ptr = buf;
             rv= 0;
             break;
         default: