Revert "Remove some designated initializers"

This reverts commit ee9eb83a84.

src/libstore/make-content-addressed.cc

@@ -56,7 +56,7 @@ std::map<StorePath, StorePath> makeContentAddressed(
                     .method = FileIngestionMethod::Recursive,
                     .hash = narModuloHash,
                 },
-                /* .references = */ std::move(refs),
+                .references = std::move(refs),
             },
             Hash::dummy,
         };