multimedia/ffmpeg: update to 4.3
New defaults (using existing dependencies):
- Enable DRM for VAAPI-capable capture on KMS console, Wayland, X11
- Enable LIBXML2 by default for DASH demuxing support [1]
Changes: https://git.ffmpeg.org/gitweb/ffmpeg.git/blob/n4.3:/Changelog
ABI: https://abi-laboratory.pro/tracker/timeline/ffmpeg/
Requested by: Tal Al <tad@vif.com> (via private mail) [1]
Reported by: portscout