landlock: Prepare to add second errata

landlock: Prepare to add second errata

Potentially include errata for Landlock ABI v5 (Linux 6.10) and v6
(Linux 6.12).  That will be useful for the following signal scoping
erratum.

As explained in errata.h, this commit should be backportable without
conflict down to ABI v5.  It must then not include the errata/abi-6.h
file.

Fixes: 54a6e6bbf3be ("landlock: Add signal scoping")
Cc: Günther Noack <gnoack@google.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250318161443.279194-5-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>