avconv: remove fake coded_frame on streamcopy hack

Back in 2002 when it was added, some muxers used information from
coded_frame. It's not true anymore, so this hack is useless and can be
removed.

avconv.c

@@ -1755,7 +1755,6 @@ static int output_packet(InputStream *ist, int ist_index,
                         abort();
                     }
                 } else {
-                    AVFrame avframe; //FIXME/XXX remove this
                     AVPacket opkt;
                     int64_t ost_tb_start_time= av_rescale_q(of->start_time, AV_TIME_BASE_Q, ost->st->time_base);
 
@@ -1771,10 +1770,6 @@ static int output_packet(InputStream *ist, int ist_index,
                     /* no reencoding needed : output the packet directly */
                     /* force the input stream PTS */
 
-                    avcodec_get_frame_defaults(&avframe);
-                    ost->st->codec->coded_frame= &avframe;
-                    avframe.key_frame = pkt->flags & AV_PKT_FLAG_KEY;
-
                     if(ost->st->codec->codec_type == AVMEDIA_TYPE_AUDIO)
                         audio_size += data_size;
                     else if (ost->st->codec->codec_type == AVMEDIA_TYPE_VIDEO) {