* lisp/ol-doi.el: New file.
* lisp/ol.el (org-link-doi-server-url): Move to new file.
(org-link--open-doi): Remove function.
* lisp/org.el (org-modules): Autoload new library for backward
compatibility.
Reported-by: yarnton--- via "General discussions about Org-mode." <emacs-orgmode@gnu.org>
<http://lists.gnu.org/r/emacs-orgmode/2020-09/msg00908.html>