* guix/build/emacs-build-system.scm (enable-autoloads-compilation)
(validate-compiled-autoloads): Add procedures.
(%standard-phases): Register the new procedures.
* gnu/packages/aux-files/emacs/guix-emacs.el (guix-emacs-find-autoloads):
Remove duplicates in the list of autoload files found.
* guix/build/emacs-utils.scm (expr->string): Add procedure.
(emacs-batch-eval, emacs-batch-edit-file): Use it.