Add the ability to parse the ALSSpecificConfig from an MPEG-4 AudioSpecificConfig. Patch by Thilo Borgmann
<com googlemail borgmann thilo> as part of GSoC 2009.


git-svn-id: file:///var/local/repositories/ffmpeg/trunk@20516 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b