playbin: shows no-audio when it's unsupported audio and does not show tags

Submitted by Bastien Nocera @hadess

Link to original bug (#351795)

Description

http://www.hadess.net/tmp/unsupported-audio.asf

(totem:10216): GStreamer-WARNING **: pad asfdemux0:audio_00 returned caps that are not a real subset of its template caps
** Message: don't know how to handle EMPTY

EMPTY in this case actually contains "Voxware Metasound" audio, which can be played with the right win32 DLLs installed.