bug#64697: 29.0.92: cannot paste NUL on macOS (regression from Emacs 28)

[Eli Zaretskii]

> Cc: Alan Third <alan@idiocy.org>
> From: Mattias Engdegård <mattias.engdegard@gmail.com>
> Date: Tue, 18 Jul 2023 10:30:38 +0200
> 
> In Emacs 29, text pasted from the clipboard on macOS will be truncated if 
> containing NULs.
> 
> Reproduction: copy text with NUL in the middle from Emacs 28 (or any other 
> application), and paste into Emacs 29.
> 
> This was probably caused by 7e3c2b553f, where construction of a Lisp string 
> was changed from make_string to build_string.
> 
> Suggested patch attached. If valid, would it qualify for emacs-29?

This is OK for emacs-29, but I wonder: do we want a unibyte string
here or a multibyte string?  We should try to call either
make_unibyte_string or make_multibyte_string accordingly, because
make_string has its own ideas about which one to produce.

Thanks.