Nix expressions for xorg.server (displaylink)

displaylink.nix

let
  pkgs = import <nixpkgs> {};
  newpkgs = pkgs.extend (self: super: {
    xorg = super.xorg // {
      xorgserver = super.xorg.xorgserver.overrideAttrs (old: {
          name = "xorg-server-1.19.6";
            src = super.fetchurl{
                url = mirror://xorg/individual/xserver/xorg-server-1.19.6.tar.bz2;
                sha256 = "15y13ihgkggmly5s07vzvpn35gzx1w0hrkbnlcvcy05h3lpm0cm7";
            };
        });
      };
    });
in
  newpkgs.xorg.xorgserver



{
nixpkgs.overlays = [
  (self: super: {
    xorg = super.xorg // {
      xorgserver = super.xorg.xorgserver.overrideAttrs (old: {
        name = "xorg-server-1.19.6";
        src = super.fetchurl{
          url = mirror://xorg/individual/xserver/xorg-server-1.19.6.tar.bz2;
          sha256 = "15y13ihgkggmly5s07vzvpn35gzx1w0hrkbnlcvcy05h3lpm0cm7";
        };
      });
    };
  })
  ];
}