Bug#1107956: release-notes: Document CET hardening for amd64 (as companion to PAC/BTI on arm64)

[Guillem Jover <guillem@debian.org>]

Package: release-notes
X-Debbugs-Cc: Emanuele Rocca <ema@debian.org>

Hi!

There was a recent addition about PAC/BTI support for arm64. I think
it would make sense to also mention the Control-flow Enforcement
Technology (CET) support for amd64, that got added at the same time,
for the same dpkg-buildflags "branch" feature, which is also enabled
by default and ends up adding the «-fcf-protection» flag.

I'm not sure whether it would be best to reword the existing
"2.2.2. PAC/BTI support on arm64" section to cover both, or to add a
new section. Let me know what you think, and I could try to propose a
patch perhaps.

Thanks,
Guillem