Motivation for this change

This already compiles fine, no changes necesssary.
I am currently working on getting DNF to compile on darwin (long story) and this is one of the less problematic dependencies :)

Example:

/nix/store/r4i8ba7cjzr1nczsqw8p9i2mjcjqifkb-libsolv-0.7.16/bin/installcheck: <arch> [options..] repo [--nocheck repo]...
	--exclude <pattern>	whitespace-separated list of (sub-)packagenames to ignore
	--withobsoletes		Check for obsoletes on packages contained in repos
	--nocheck		Do not warn about all following repos (only use them to fulfill dependencies)
	--withsrc		Also check dependencies of src.rpm

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)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.