Draft: main/xz: add snapshot function, update source, fix sabotaged landlock sandbox check, add xz-lang subpackage
main/xz: add snapshot function and update source
First Commit: The currently referenced GitHub repo has been disabled and Lasse's cgit interface has server-side snapshots disabled. Hence, add a snapshot function to ease creating our own snapshot and update the source URL to point to the created snapshot.
main/xz: add xz-lang subpackage
Second Commit: As the commit title says...
Edited by Marian Buschsieweke