The header files with constants and structures for audio specific
interaction with Pulseaudio are suppose to be under LGPL license.
For some odd reason a2dp-codecs.h ended up being under GPL license
which is against the intention of this being shared and re-used by
non-GPL programs. Fix this now to avoid any future confusion.
This pulls a2dp-codecs.h from BlueZ which contains the capabilities
structures for SBC and MPEG. We currently have these manually added to
ipc.h, so pulling this header makes our files identical to upstream.
