audio: enable compilation without flag TARGET_USES_AOSP_FOR_AUDIO

- Disable some features to enable compilation without AOSP flag.
- Add new feature flags to guard legacy features not
  required on O.
- Update channel index used for surround sound recording as per
  latest channel mapping index.

Change-Id: I4d2654b8c8938dea60388524ebb43980a3fd8c3d