nix: simplify the vulkan-loader linking

flake.nix

@@ -36,13 +36,9 @@
           # enables debug builds, if we want: https://github.com/NixOS/nixpkgs/issues/60919.
           hardeningDisable = [ "fortify" ];
 
-          postFixup = let
-            libPath = nixpkgs.lib.makeLibraryPath [ pkgs.vulkan-loader ];
-          in ''
+          preFixup = ''
             # strictly speaking not *all* binaries need this, but this is easy.
-            # might be better to use `wrapProgram`, not sure.
-            echo adding rpath "${libPath}"
-            patchelf --add-rpath "${libPath}" $out/bin/*
+            patchelf --add-needed ${pkgs.vulkan-loader}/lib/libvulkan.so.1 $out/bin/*
           '';
         };
       };