Enforce ld.gold is installed and show its version

[Bronek]

This does not actually add ld.gold to our docker images (since binutils is a required dependency and contains gold in all the distros we currently support), however it does make it explicit and shows its version. Might be also useful for the future, if ld.gold is no longer installed by default (e.g. Debian Trixie)

[bthomee]

Since we currently don't use gold, and knowing that it's already deprecated and slated to be removed at some point, what's the benefit of adding it now and then having the pipeline fail when it's gone?

[Bronek]

Turns out, we do use gold. It is installed by default by the binutils package, and used by default for gcc builds, if installed.

As for the latter question, the binutils versions in all of the distros we use (Debian, Ubuntu, RHEL) are old enough not to be affected by the announcement from GNU, e.g. RHEL 9.6 is on version 2.35 ; Ubuntu Noble version 2.42 ; Debian Bookworm version 2.40. We would only need to explicitly install binutils-gold for Debian Trixie and that would be version 2.44

The addition of binutils-gold package is basically future-proofing until we switch to another linker, and that decision belongs to XRPLF projects such as rippled, not to CI.

[bthomee]

Is your PR description still accurate?

This does not actually add ld.gold to our docker images

[Bronek]

Is your PR description still accurate?

This does not actually add ld.gold to our docker images

Yes. ld.gold is added by binutils which we implicitly have installed (because it is required dependency when you want to use any compiler).

With the addition of binutils-gold we make it explicit that we want this linker - rather than rely on what the current distro release is serving.

$ dpkg -S `which ld.gold`
binutils: /usr/bin/ld.gold