Mark nnheader-cancel-timer as obsolete and adjust callers

* lisp/gnus/nnheader.el (nnheader-cancel-timer)
(nnheader-cancel-function-timers): Mark as obsolete.

* lisp/gnus/nntp.el (nntp-with-open-group-function)
(nntp-async-stop): Adjust caller.

* lisp/gnus/gnus-art.el (gnus-stop-date-timer): Ditto.

* lisp/gnus/gnus-async.el (gnus-async-prefetch-next): Ditto.

* lisp/gnus/gnus-demon.el (gnus-demon-run-callback)
(gnus-demon-cancel): Ditto.

* lisp/gnus/mail-source.el (mail-source-report-new-mail): Ditto.

* lisp/gnus/nnmaildir.el (nnmaildir-request-accept-article): Ditto.
1 job for master in 6 minutes and 26 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
failed #1859
test-all

00:06:26

 
Name Stage Failure
failed
test-all Test
make[2]: *** [bootstrap-emacs.pdmp] Error 255
Makefile:807: recipe for target 'bootstrap-emacs.pdmp' failed
make[2]: Leaving directory '/builds/emacs/emacs/src'
Makefile:424: recipe for target 'src' failed
make[1]: *** [src] Error 2
make[1]: Leaving directory '/builds/emacs/emacs'
Makefile:1115: recipe for target 'bootstrap' failed
make: *** [bootstrap] Error 2
ERROR: Job failed: exit code 1