exult: add license

see issue #43716

+1
+1
pkgs/games/exult/default.nix
··· 46 maintainers = [ stdenv.lib.maintainers.eelco ]; 47 platforms = stdenv.lib.platforms.unix; 48 hydraPlatforms = stdenv.lib.platforms.linux; # darwin times out 49 }; 50 }
··· 46 maintainers = [ stdenv.lib.maintainers.eelco ]; 47 platforms = stdenv.lib.platforms.unix; 48 hydraPlatforms = stdenv.lib.platforms.linux; # darwin times out 49 + license = stdenv.lib.licenses.gpl2Plus; 50 }; 51 }