commandergenius: fix X11 includes

The SDL2 compatibility layer still includes X11 libraries in some
of its headers [1], which breaks the build of commandergenius if
`xorg.libX11` is not included as build input.

[1]: https://github.com/libsdl-org/sdl2-compat/blob/291749630d731d45f7a5ff3d4b2429fbeb58ac4c/include/SDL2/SDL_syswm.h#L68

pkgs/by-name/co/commandergenius/package.nix

@@ -14,6 +14,7 @@
   SDL2_mixer,
   SDL2_ttf,
   python3,
+  xorg,
 }:
 
 stdenv.mkDerivation rec {
@@ -38,6 +39,7 @@ stdenv.mkDerivation rec {
     zlib
     curl
     python3
+    xorg.libX11
   ];
 
   cmakeFlags = [