lavf/riffdec: Remove \n from avpriv_report_missing_feature().

Found-by: Clément Bœsch

libavformat/riffdec.c

@@ -131,7 +131,7 @@ int ff_get_wav_header(AVFormatContext *s, AVIOContext *pb,
     if (size >= 18 && id != 0x0165) {  /* We're obviously dealing with WAVEFORMATEX */
         int cbSize = avio_rl16(pb); /* cbSize */
         if (big_endian) {
-            avpriv_report_missing_feature(codec, "WAVEFORMATEX support for RIFX files\n");
+            avpriv_report_missing_feature(codec, "WAVEFORMATEX support for RIFX files");
             return AVERROR_PATCHWELCOME;
         }
         size  -= 18;