Pacify recent unused/ignored lexvar warnings

Pacify recent unused/ignored lexvar warnings

Lexvars with special names like 'ignored' or 'unused' are no longer
treated specially.

* lisp/ansi-color.el (ansi-color-process-output):
* lisp/cus-edit.el (customize-apropos-options):
* lisp/cus-theme.el (customize-create-theme):
* lisp/dired-aux.el (dired-hide-all):
* lisp/emacs-lisp/crm.el (crm--choose-completion-string):
* lisp/emacs-lisp/tabulated-list.el (tabulated-list-revert):
* lisp/ido.el (ido-choose-completion-string):
* lisp/international/mule-diag.el (describe-font-internal):
* lisp/mail/sendmail.el (sendmail-user-agent-compose):
* lisp/progmodes/fortran.el (fortran-uncomment-region):
* lisp/progmodes/prolog.el (prolog-inferior-guess-flavor):
* lisp/progmodes/ruby-mode.el (ruby-indent-line, ruby-indent-exp):
* lisp/url/url.el (url-mm-callback):
* lisp/xwidget.el (xwidget-webkit-history-reload): Prepend an
underscore to unused function parameter names.
* lisp/emacs-lisp/cconv.el (cconv--dummy-var): Remove unused
constant.
* lisp/files.el (hack-local-variables-filter): Remove unused lexvar.