mpegaudiodec_template: fix leaking fdsp for mp3on4float

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>

libavcodec/mpegaudiodec_template.c

@@ -1828,6 +1828,9 @@ static av_cold int decode_close_mp3on4(AVCodecContext * avctx)
     MP3On4DecodeContext *s = avctx->priv_data;
     int i;
 
+    if (s->mp3decctx[0])
+        av_freep(&s->mp3decctx[0]->fdsp);
+
     for (i = 0; i < s->frames; i++)
         av_freep(&s->mp3decctx[i]);