Installing the man pages is a bit more tricky. The configure script
completely disables the documentation unless latex2man is found.
However, just installing the man pages can be done without latex2man,
because the man pages are pre-built in the source tarball. Therefore
we pass ${coreutils}/bin/true as latex2man, which allows to install
the pre-build man pages without depending on full texlive.

Motivation for this change

It's useful to have the documentation matching the installed package.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after) => No change
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.