MFH: r395769

multimedia/libav: update to 11.4

Changes: https://git.libav.org/?p=libav.git;a=blob;f=Changelog;hb=refs/tags/v11.4
Security: da434a78-e342-4d9a-87e2-7497e5f117ba
Security: 80c66af0-d1c5-449e-bd31-63b12525ff88
Approved by: ports-secteam (feld)