Update multimedia/libdvdread and multimedia/libdvdnav to 6.1.0
Changelogs are available here:
https://code.videolan.org/videolan/libdvdread/-/blob/master/NEWS
https://code.videolan.org/videolan/libdvdnav/-/blob/master/ChangeLog
Also, bump dependent ports' revisions and mark sysutils/dvdbackup as BROKEN [1]
Approved by: ehaupt [1]