[bug#29828] Various Linter corrections

[ng0]

This bug starts a series of patches to:
 - fix complains external linters found
 - fix complains our linter found
These fixes include: addressing permanent redirects,
404s -> new files, domains, URLs, etc.

4 Patches for the start, more to follow.
-- 
GnuPG: A88C8ADD129828D7EAC02E52E22F9BBFEE348588
GnuPG: https://c.n0.is/ng0_pubkeys/tree/keys
  WWW: https://n0.is

0001-gnu-xz-Adjust-the-home-page.patch
Description: Text document

0002-gnu-xdelta-Change-to-new-home-page.patch
Description: Text document

0003-gnu-java-xz-Adjust-home-page.patch
Description: Text document

0004-gnu-ruby-Use-new-home-page.patch
Description: Text document

signature.asc
Description: PGP signature