Timestamps in two FATE H.264 conformance tests now start at 1 instead
of 0, which also happens in some other H.264 tests before this commit
and so is not a big issue.
Conversely, timestamps in some HEVC conformance tests start from a
smaller value now.
Ideally this should be addressed later in a more general way.
h264-conformance-frext-frext2_panasonic_b no longer requires -vsync
passthrough.
ba4b73c977