Motivation for this change

DRAT-trim is a tool which can be used to make SAT solvers (such as
glucose and glucose-syrup, which are in nixpkgs) more useful by
checking their work. It has become well-accepted in the SAT solver
development community and has been used in the annual SAT competitions
for the last few years.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option build-use-sandbox in nix.conf on non-NixOS)
• 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 nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.