dosemu_fonts: add license

pkgs/data/fonts/dosemu-fonts/default.nix

···
-{ stdenv, fetchurl, bdftopcf, mkfontdir, mkfontscale }:
+{ lib, stdenv, fetchurl, bdftopcf, mkfontdir, mkfontscale }:
 
 stdenv.mkDerivation rec {
   pname = "dosemu-fonts";
···
 
   meta = {
     description = "Various fonts from the DOSEmu project";
+    license = lib.licenses.gpl2Only;
   };
 }