Use version-list-* functions in package.el.

* emacs-lisp/package-x.el (package-upload-buffer-internal): Use
version-to-list.
(package-upload-buffer-internal): Use version-list-<=.

* emacs-lisp/package.el (package-version-split)
(package--version-first-nonzero, package-version-compare):
Functions removed.
(package-directory-list, package-load-all-descriptors)
(package--built-in, package-activate, define-package)
(package-installed-p, package-compute-transaction)
(package-read-all-archive-contents)
(package--add-to-archive-contents, package-buffer-info)
(package-tar-file-info, package-list-packages-internal): Use
version-to-list and version-list-*.