Work around recent MELPA -pkg.el change

MELPA c. 2024-09-29 started to add a header line in each -pkg.el file:

  ";; -*- mode: lisp-data; no-byte-compile: t; lexical-binding: nil -*-\n"

This causes package-install to barf on older Emacs where
lisp-data-mode is undefined.

Mitigate by defalias-ing lisp-data-mode to normal-mode.

Makefile

@@ -50,6 +50,7 @@ melpa-url := https://melpa.org/packages/
 deps:
 	$(batch-emacs) \
       --eval '(add-to-list (quote package-archives) (cons "melpa" "$(melpa-url)"))' \
+      --eval '(unless (fboundp (quote lisp-data-mode)) (defalias (quote lisp-data-mode) (quote normal-mode)))' \
       --eval '(package-refresh-contents)' \
       --eval '(package-install (quote faceup))' \
       --eval '(package-install (quote paredit))'