bug#18034: Bug #18034: toggle-read-only used in the code

[Noam Postavsky <npostavs@users.sourceforge.net>]

# I accidentally marked 18034 fixed due to typo but I meant 18039
fixed 18039 25.0.94
quit

However, this bug is fixed as well. I ran the find+gawk expression
against emacs-25 sources, only 3 occurences left, and they are
acceptable uses kept for backwards compat reasons. I've added context
to each hit:

~/src/emacs$ find emacs-25/lisp/ -type f -name \*.el       -exec gawk
'FILENAME ~ /\<files\.el$/ || /^\s*[;"]|"$/ { next; }
                  /[^-[:alnum:]]toggle-read-only\>/ {
                      print FILENAME ":" FNR ":\t" $0;
                  }' {} +

;; toggle-read-only is obsolete since 24.3, but since vc-t-r-o was made
;; obsolete earlier, it is ok for the latter to be an alias to the former,
;; since the latter will be removed first.  We can't just make it
;; an alias for read-only-mode, since that is not 100% the same.
emacs-25/lisp/vc/vc-hooks.el:573:    (defalias 'vc-toggle-read-only
'toggle-read-only)

    (substitute-key-definition
     'read-only-mode 'hide-ifdef-toggle-outside-read-only map)
    ;; `toggle-read-only' is obsoleted by `read-only-mode'.
    (substitute-key-definition
emacs-25/lisp/progmodes/hideif.el:195:         'toggle-read-only
'hide-ifdef-toggle-outside-read-only map)

    (define-key map [remap read-only-mode] 'dired-toggle-read-only)
    ;; `toggle-read-only' is an obsolete alias for `read-only-mode'
emacs-25/lisp/dired.el:1561:        (define-key map [remap
toggle-read-only] 'dired-toggle-read-only)