bug#35645: Fix icalendar--add-diary-entry/diary-make-entry interaction

[Eli Zaretskii]

> From: Ulf Jasper <ulf.jasper@web.de>
> Date: Mon, 03 Jun 2019 20:30:13 +0200
> Cc: 35645@debbugs.gnu.org, Noam Postavsky <npostavs@gmail.com>
> 
> Am 23.05.2019 um 22:49 (-0400) schrieb Thomas Fitzsimmons:
> >
> > Ulf, the only other feedback I have for icalendar is that
> > icalendar--add-diary-entry is useful to/used by other packages (e.g.,
> > Excorporate) despite it being a private function.  What if we added a
> > public alias, icalendar-add-diary-entry, within this same patch?  Then I
> > could check for that alias's existence and only enable the workaround
> > advice for older Emacs versions.
> >
> 
> Could you please provide a patch with all the changes we want to make?

Ping!  Thomas, could you please provide a patch as Ulf requested?  We
would like to proceed with fixing this issue.

TIA