MFH: r556125

multimedia/dav1d: update to 0.8.0

Changes: https://code.videolan.org/videolan/dav1d/-/tags/0.8.0
Changes: https://code.videolan.org/videolan/dav1d/-/blob/0.8.0/NEWS
Changes: https://code.videolan.org/videolan/dav1d/compare/0.7.1...0.8.0
Approved by: ports-secteam blanket (required by Firefox 82)