lavc: remove libfaac wrapper

lavc: remove libfaac wrapper

There is really no need for two aac wrappers, we already have
libfdk-aac which is better. Not to mention that faac doesn't
even support HEv1, or HEv2. It's also under a license which is
unusable for distribution, so it would only be useful to people
who will compile their own ffmpeg, only use it themselves (which
at that point should just use fdk-aac).

Signed-off-by: Josh de Kock <josh@itanimul.li>