Recent defcustom's with ':safe t'

[Kyle Meyer]

There are handful of defcustom's that declare ':safe t':

    $ git rev-parse HEAD
    be7ad3124631178abb2c9c081ddc00bd3057e11b

    $ git grep ':safe t'
    lisp/ob-csharp.el:  :safe t)
    lisp/ob-csharp.el:  :safe t)
    lisp/ob-ditaa.el:  :safe t)
    lisp/ob-tangle.el:  :safe t)
    lisp/oc-bibtex.el:  :safe t)
    lisp/ol.el:  :safe t)
    lisp/ol.el:  :safe t)
    lisp/ol.el:  :safe t)
    lisp/org-archive.el:  :safe t)
    lisp/org-cycle.el:  :safe t)
    lisp/org-id.el:  :safe t)
    lisp/org-src.el:  :safe t)
    lisp/org.el:  :safe t)
    lisp/org.el:  :safe t)
    lisp/org.el:  :safe t)
    lisp/org.el:  :safe t)
    lisp/org.el:  :safe t)
    lisp/ox-html.el:  :safe t)
    lisp/ox-html.el:  :safe t)
    lisp/ox-html.el:  :safe t)
    lisp/ox-html.el:  :safe t)
    lisp/ox-md.el:  :safe t)
    lisp/ox-odt.el:  :safe t)
    lisp/ox-odt.el:  :safe t)

Many of these were added in 4b5abdd6d (Add missing :safe for
defcustoms added/changed in Org 9.8, 2026-02-14).

As far as I understand, that's invalid.  See Emacs's 4341e79a5fa (Remove
bogus ":safe t" custom properties, 2021-10-02), which previously pruned
a bunch of these from Org's tree.

Likewise, I think ':safe nil' properties should be removed, for the
reason given in Emacs's 62d6cecfcd1 (Remove bogus ":safe nil" custom
properties, 2021-10-02).