libutil: Make AutoDelete non-copyable and non-movable

This is a good precaution, since we don't want to delete
directories twice accidentally.

(cherry picked from commit 40e3f5c0a4)

src/libutil/include/nix/util/file-system.hh

@@ -287,6 +287,10 @@ class AutoDelete
 public:
     AutoDelete();
     AutoDelete(const std::filesystem::path & p, bool recursive = true);
+    AutoDelete(AutoDelete &&) = delete;
+    AutoDelete(const AutoDelete &) = delete;
+    AutoDelete & operator=(AutoDelete &&) = delete;
+    AutoDelete & operator=(const AutoDelete &) = delete;
     ~AutoDelete();
 
     void cancel();