This fixes warnings that 'isom' can only be a compatible instead of major brand. Issue #755.
Required by ISO/IEC 14496-14:2018 and ISO/IEC 23000-19:2018. Issue #755.
- Support decryption verification in _CheckTestResults - Allow diff_files in _CheckTestResults - Update all functional tests to use _CheckTestResults Change-Id: I3f9c02f35808eba787becf9b1e5c1ce9238f943e