Added Dolby Vision backward compatible signalling, i.e. for Dolby Vision
profile 8, both base codec without Dolby Vision and HDR codec with Dolby
Vision are signalled.
This is achieved by using a new MuxerListener implementation
MultiCodecMuxerListener, which wraps multiple child MuxerListeners and
is able to delegate to the child MuxerListeners based on the codecs in
the stream.
Closes#341.
Change-Id: I1967bb1ed503087cdd011c364e5fb5647d516ca4
KongQun Yang