devilutionx: pass static version of SDL2 into derivation

pkgs/games/devilutionx/default.nix

···
   buildInputs = [
     fmt
     libpng
-    (SDL2.override { withStatic = true; })
+    SDL2
     SDL2_image
   ];
 

pkgs/top-level/all-packages.nix

···
 
   ddnet = callPackage ../games/ddnet { };
 
-  devilutionx = callPackage ../games/devilutionx {};
+  devilutionx = callPackage ../games/devilutionx {
+    SDL2 = SDL2.override {
+      withStatic = true;
+    };
+  };
 
   dhewm3 = callPackage ../games/dhewm3 {};