codecmap: Don't create dummy extradata for AAC LATM

If extradata is created for LATM, libav will use it for initialising AAC
decoder and decoding will fail.

Fixes bug #652812.

ext/ffmpeg/gstffmpegcodecmap.c

@@ -2387,7 +2387,7 @@ gst_ffmpeg_caps_with_codecid (enum CodecID codec_id,
     }
 
     GST_DEBUG ("have codec data of size %d", size);
-  } else if (context->extradata == NULL) {
+  } else if (context->extradata == NULL && codec_id != CODEC_ID_AAC_LATM) {
     /* no extradata, alloc dummy with 0 sized, some codecs insist on reading
      * extradata anyway which makes then segfault. */
     context->extradata =