openra: adding individual executables for each mod

OpenRA desktop configuration files presently fail to launch the various mods, as the executable files (`openra-ra` for Red Alert, `openra-cnc` for Tiberian Dawn and `openra-d2k` for Dune 2K) they rely on are not present in this package.

pkgs/games/openra/default.nix

@@ -69,5 +69,11 @@ stdenv.mkDerivation rec {
 
     mkdir -p $out/bin
     makeWrapper $out/lib/openra/launch-game.sh $out/bin/openra --run "cd $out/lib/openra"
+    printf "#!/bin/sh\nexec $out/bin/openra Game.Mod=ra" > $out/bin/openra-ra
+    chmod +x $out/bin/openra-ra
+    printf "#!/bin/sh\nexec $out/bin/openra Game.Mod=cnc" > $out/bin/openra-cnc
+    chmod +x $out/bin/openra-cnc
+    printf "#!/bin/sh\nexec $out/bin/openra Game.Mod=d2k" > $out/bin/openra-d2k
+    chmod +x $out/bin/openra-d2k
   '';
 }