rsodec: Use avpriv_report_missing_feature() where appropriate

libavformat/rsodec.c

@@ -43,7 +43,7 @@ static int rso_read_header(AVFormatContext *s)
     codec = ff_codec_get_id(ff_codec_rso_tags, id);
 
     if (codec == AV_CODEC_ID_ADPCM_IMA_WAV) {
-        av_log(s, AV_LOG_ERROR, "ADPCM in RSO not implemented\n");
+        avpriv_report_missing_feature(s, "ADPCM in RSO");
         return AVERROR_PATCHWELCOME;
     }