wav: remove an invalid free().

Signed-off-by: Anton Khirnov <anton@khirnov.net>

libavformat/wav.c

@@ -52,7 +52,6 @@ static int wav_write_header(AVFormatContext *s)
     if (ff_put_wav_header(pb, s->streams[0]->codec) < 0) {
         av_log(s, AV_LOG_ERROR, "%s codec not supported in WAVE format\n",
                s->streams[0]->codec->codec ? s->streams[0]->codec->codec->name : "NONE");
-        av_free(wav);
         return -1;
     }
     ff_end_tag(pb, fmt);