net/liveMedia: Update to 2026.10.13

Add local backup to MASTER_SITES. Upstream doesn't keep an archive of
older releases, so I've set up a script to automatically archive them
locally and to remind me to update the port. This is a team port, so if
anyone else on multimedia@ wants the script, just let me know, but for
now, I'm limited to using my own public_distfiles dir on freefall.

https://download.live555.com/changelog.txt

MFH: 2026Q4