(with-demoted-errors): Warn on missing format arg

The `format` arg has been mandatory for a while, but the backward
compatibility code that handled the case of a missing `format` arg
made it hard to notice when using the old calling convention.

* lisp/subr.el (with-demoted-errors): Warn on missing `format` arg.

* lisp/emacs-lisp/smie.el (smie-indent--separator-outdent): Don't abuse
`with-demoted-errors`.
(smie-indent-line, smie-auto-fill):
* test/lisp/emacs-lisp/ert-tests.el (ert-test-with-demoted-errors):
* lisp/vc/vc-hooks.el (vc-refresh-state):
* lisp/vc/vc-annotate.el (vc-annotate-background-mode):
* lisp/vc/diff-mode.el (diff-syntax-fontify-hunk):
* lisp/textmodes/reftex-toc.el (reftex-re-enlarge):
* lisp/progmodes/sh-script.el (sh-smie-sh-rules):
* lisp/progmodes/octave.el (inferior-octave-startup):
* lisp/pcmpl-gnu.el (pcmpl-gnu-make-all-targets):
* lisp/org/org-refile.el (org-refile):
* lisp/org/org-capture.el (org-capture-store-last-position):
* lisp/nxml/nxml-mode.el (nxml-mode):
* lisp/notifications.el (notifications-notify):
* lisp/gnus/mm-view.el (mm-display-inline-fontify):
* lisp/finder.el (finder-unload-function):
* lisp/files.el (safe-local-variable-p, backup-buffer-copy
* lisp/autorevert.el (auto-revert-notify-handler):
Pass `format` arg to `with-demoted-errors`.

lisp/nxml/nxml-mode.el

@@ -566,7 +566,8 @@ Many aspects this mode can be customized using
           (font-lock-syntactic-face-function
            . sgml-font-lock-syntactic-face)))
 
-  (with-demoted-errors (rng-nxml-mode-init)))
+  (with-demoted-errors "RNG NXML error: %S"
+    (rng-nxml-mode-init)))
 
 (defun nxml--buffer-substring-filter (string)
   ;; The `rng-state' property is huge, so don't copy it to the kill ring.