links: 2.15 -> 2.16

Semi-automatic update generated by https://github.com/ryantm/nixpkgs-update tools.

This update was made based on information from https://repology.org/metapackage/links2/versions.

These checks were done:

- built on NixOS
- Warning: no binary found that responded to help or version flags. (This warning appears even if the package isn't expected to have binaries.)
- found 2.16 with grep in /nix/store/bqfvaiwnj8bg69d0amarchz9yq7hsg8l-links2-2.16
- directory tree listing: https://gist.github.com/63794d9062d2bfacd2eb8e3d67b1e882
- du listing: https://gist.github.com/d1615a45d8130ac6fdfa50f96b788387