This feeds into efforts to create a working install target.
The order of headers is still funky, and was "fixed" by clang-format,
but in a way that doesn't exactly align with the style guide. Further
cleanup of header order is coming in a follow-up PR.
- Because MpdBuilder no longer sets ContentProtection, live was broken.
- For key-rotation, <cenc:pssh> element is updated.
Change-Id: I45bb80a12faff39ccf5deb82439c0732ed9cea59