fftools/ffmpeg: drop outdated comments

fftools/ffmpeg.c

@@ -1431,7 +1431,6 @@ int main(int argc, char **argv)
         exit_program(1);
     }
 
-    /* file converter / grab */
     if (nb_output_files <= 0) {
         av_log(NULL, AV_LOG_FATAL, "At least one output file must be specified\n");
         exit_program(1);

fftools/ffmpeg_demux.c

@@ -1569,7 +1569,6 @@ int ifile_open(const OptionsContext *o, const char *filename)
 
     d->thread_queue_size = o->thread_queue_size;
 
-    /* update the current parameters so that they match the one of the input stream */
     add_input_streams(o, d);
 
     /* dump the file content */