Prefer incf to cl-incf in gnus/*.el

Prefer incf to cl-incf in gnus/*.el

* lisp/gnus/gnus-agent.el (gnus-agent-load-local)
(gnus-agent-expire-group-1, gnus-agent-update-files-total-fetched-for):
* lisp/gnus/gnus-art.el (gnus-article-header-rank):
* lisp/gnus/gnus-async.el (gnus-async-wait-for-article):
* lisp/gnus/gnus-cache.el (gnus-cache-update-file-total-fetched-for):
* lisp/gnus/gnus-registry.el (gnus-registry-import-eld):
* lisp/gnus/gnus-salt.el (gnus-pick-line-number, gnus-tree-minimize)
(gnus-generate-vertical-tree):
* lisp/gnus/gnus-spec.el (gnus-correct-substring):
* lisp/gnus/gnus-start.el (gnus-ask-server-for-new-groups, gnus-method-rank):
* lisp/gnus/gnus-sum.el (gnus-data-update-list)
(gnus-summary-number-of-articles-in-thread, gnus-build-sparse-threads)
(gnus-summary-prepare-threads, gnus-invisible-cut-children)
(gnus-summary-limit-children, gnus-expunge-thread)
(gnus-summary-refer-references, gnus-summary-update-mark)
(gnus-summary-hide-all-threads, gnus-summary-save-parts-1):
* lisp/gnus/gnus-topic.el (gnus-topic-articles-in-topic)
(gnus-topic-prepare-topic, gnus-topic-display-missing-topic)
(gnus-topic-update-topic-line):
* lisp/gnus/gnus-uu.el (gnus-uu-post-encoded):
* lisp/gnus/gnus-win.el (gnus-configure-frame):
* lisp/gnus/mail-source.el (mail-source-fetch-directory)
(mail-source-fetch-maildir, mail-source-fetch-imap):
* lisp/gnus/message.el (message-remove-header)
(message-remove-first-header, message-make-caesar-translation-table):
* lisp/gnus/mm-encode.el (mm-qp-or-base64):
* lisp/gnus/mml.el (mml-compute-boundary, mml-compute-boundary-1):
* lisp/gnus/nnatom.el (nnatom--read-links):
* lisp/gnus/nnbabyl.el (nnbabyl-retrieve-headers):
* lisp/gnus/nndoc.el (nndoc-oe-dbx-dissection, nndoc-dissect-buffer)
(nndoc-dissect-mime-parts-sub):
* lisp/gnus/nneething.el (nneething-retrieve-headers):
* lisp/gnus/nnheader.el (nnheader-generate-fake-message-id)
(nnheader-insert-head, nnheader-translate-file-chars):
* lisp/gnus/nnimap.el (nnimap-find-wanted-parts-1)
(nnimap-retrieve-group-data-early, nnimap-send-command):
* lisp/gnus/nnmail.el (nnmail-process-babyl-mail-format)
(nnmail-process-unix-mail-format, nnmail-process-mmdf-mail-format)
(nnmail-get-new-mail-1):
* lisp/gnus/nnmaildir.el (nnmaildir--scan):
* lisp/gnus/nnrss.el (nnrss-check-group):
* lisp/gnus/nnselect.el (nnselect-request-thread):
* lisp/gnus/nnspool.el (nnspool-retrieve-headers):
* lisp/gnus/nntp.el (nntp-retrieve-headers)
(nntp-finish-retrieve-group-infos, nntp-retrieve-groups)
(nntp-retrieve-articles, nntp-retrieve-headers-with-xover):
* lisp/gnus/nnvirtual.el (nnvirtual-create-mapping):
* lisp/gnus/nnweb.el (nnweb-google-parse-1, nnweb-google-create-mapping)
(nnweb-gmane-create-mapping):
* lisp/gnus/spam.el (spam-resolve-registrations-routine): Prefer incf to
cl-incf.

(cherry picked from commit ae8522af41bb67bf417b94ed54146a43fe2150ec)