Bug 1073805 - Fix HE-AAC regression on windows. r=kinetik,cpearce a=lmandel

When we switched to the stagefright mp4 demuxer, we fed aac
to the platform decoders with ADTS encapsulation instead
of letting the platform's demuxer to handle the mp4 container
directly.

Unfortunately ADTS only supports AAC profile 1-4, so we stopped
supporting profile 5 (HE-AAC with Spectral Band Replication).

Windows Media Framework will accept raw aac, so we move the
application of the ADTS headers to the individual platform
decoder modules, and then pass unframed packets on Windows.

All other platforms add the ADTS header so the behaviour and
support there will be the same as before.