ffmpeg_demux: don't print input error for AVERROR_EXIT

This error code is for expected exits, like after listing options for a
device.

fftools/ffmpeg_demux.c

@@ -1726,6 +1726,7 @@ int ifile_open(const OptionsContext *o, const char *filename, Scheduler *sch)
     /* open the input file with generic avformat function */
     err = avformat_open_input(&ic, filename, file_iformat, &o->g->format_opts);
     if (err < 0) {
+        if (err != AVERROR_EXIT)
             av_log(d, AV_LOG_ERROR,
                    "Error opening input: %s\n", av_err2str(err));
         if (err == AVERROR_PROTOCOL_NOT_FOUND)