Missing c++ headers after upgrade from 13.2-RELEASE to 14.0-RC1

From: Renato Botelho <garga_at_FreeBSD.org>
Date: Mon, 16 Oct 2023 12:32:03 UTC
I've installed a FreeBSD 13.2-RELEASE and immediately upgraded it to 
14.0-RC1 using freebsd-update.  During second call to `freebsd-update 
install` I got following warnings:

install: ///usr/include/c++/v1/__string exists but is not a directory
install: ///usr/include/c++/v1/__string/char_traits.h: Not a directory
install: ///usr/include/c++/v1/__string/extern_template_lists.h: Not a 
directory

While it was still running I checked and /usr/include/c++/v1/__string 
was a plain file.  After upgrade finished, I checked again and 
/usr/include/c++/v1/__string was missing.
-- 
Renato Botelho