games/anki: Update to 2.1.16
* Backport two patches from upstream that fix the argument handling with
multimedia/mpv since r520597.
* Also slightly change the MASTER_SITES as upstream distribute tarballs for
newer versions only via GitHub.
Although there are already some newer releases available use the 2.1.16
release for a while. It's mainly because the build process has changed a
lot since the 2.1.17 release and still needs to be investigated a little
more closely.
Changelog:
https://apps.ankiweb.net/docs/changes.html#changes-in-2.1.16
Approved by: ports-secteam bugfix blanket
7b77e19910