aacenc: Fix bug in writing libavcodec_ident.

the written length was off by 2 causing aac decoders to fail with the data.
lucky the encoder was marked as experimental and not used much

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/aacenc.c

@@ -488,7 +488,7 @@ static void put_bitstream_info(AVCodecContext *avctx, AACEncContext *s,
     put_bits(&s->pb, 3, TYPE_FIL);
     put_bits(&s->pb, 4, FFMIN(namelen, 15));
     if (namelen >= 15)
-        put_bits(&s->pb, 8, namelen - 16);
+        put_bits(&s->pb, 8, namelen - 14);
     put_bits(&s->pb, 4, 0); //extension type - filler
     padbits = 8 - (put_bits_count(&s->pb) & 7);
     avpriv_align_put_bits(&s->pb);