MFH: r514302

multimedia/dav1d: update to 0.5.0

Changes: https://code.videolan.org/videolan/dav1d/tags/0.5.0
Changes: https://code.videolan.org/videolan/dav1d/blob/0.5.0/NEWS
Changes: https://code.videolan.org/videolan/dav1d/compare/0.4.0...0.5.0
Approved by: ports-secteam blanket (required by Firefox 71)