make av_find_stream_info find frame_size for aac too

Originally committed as revision 13976 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/utils.c

@@ -1729,7 +1729,9 @@ static int has_codec_parameters(AVCodecContext *enc)
     switch(enc->codec_type) {
     case CODEC_TYPE_AUDIO:
         val = enc->sample_rate && enc->channels;
-        if(enc->codec_id == CODEC_ID_VORBIS && !enc->frame_size)
+        if(!enc->frame_size &&
+           (enc->codec_id == CODEC_ID_VORBIS ||
+            enc->codec_id == CODEC_ID_AAC))
             return 0;
         break;
     case CODEC_TYPE_VIDEO: