devel/magit*: Add upstream patch to fix warning message

With recent Emacs 31 following warning message is displayed when
evaluating "(require 'magit)"

Warning (files): Missing ‘lexical-binding’ cookie in "/usr/local/share/emacs/31.0.50/site-lisp/magit/magit-version.el".

So add upstream patch to fix it.

While here, tidy up Makefile with portfmt.