multimedia/libdvd{read,nav}: Update to latest version
Update libdvdread to 6.1.2, changelog:
https://code.videolan.org/videolan/libdvdread/-/blob/master/NEWS
Update libdvdnav to 6.1.1, changelog:
https://code.videolan.org/videolan/libdvdnav/-/blob/master/ChangeLog
and bump dependent ports' revisions.