Revert "emacs: disable __structuredAttrs for elisp packages for now" (#398988)

Author: jian-lin

pkgs/applications/editors/emacs/build-support/generic.nix

@@ -61,8 +61,7 @@ lib.extendMkDerivation {
       propagatedUserEnvPkgs = finalAttrs.packageRequires ++ propagatedUserEnvPkgs;
 
       strictDeps = args.strictDeps or true;
-      # TODO re-enable after #392928 reaches master
-      # __structuredAttrs = args.__structuredAttrs or true;
+      __structuredAttrs = args.__structuredAttrs or true;
 
       inherit turnCompilationWarningToError ignoreCompilationError;