upstream: GUIX closure contains too much unnecessary stuff

[laanwj]

The minimum guix closure contains X11 libraries, graphviz, as well as LaTeX and associated fonts. They should be unnecessary for minimum set of packages needed to build. Especially on slower CPUs (eg current RISC-V cores, qemu) it results in a large slowdown, it's also bad from a "minimum trusted set" point of view.

They're pulled in by guix-manual, as well as sometimes, package-specific documentation. Unfortunately, documentation is not behind an optional flag at the moment so there's nothing we can do at our build system level. Our manifest.scm already contains nothing that depends on them, and they're not part of our build environment.

Upstream issues about it (will update when i come across more):
https://issues.guix.gnu.org/issue/63050

[fanquake]

Related upstream change: https://git.savannah.gnu.org/cgit/guix.git/commit/?id=7b0f145802f0c2c785014293d748721678fef824.