bug#41232: [PATCH] Avoid a segfault when processing disable-eval specs

[Eli Zaretskii]

> From: Clément Pit-Claudel <cpitclaudel@gmail.com>
> Date: Wed, 13 May 2020 10:40:18 -0400
> 
> The following code causes Emacs to segfault:
> 
>   (insert (propertize "A" 'display '(disable-eval . nil)))
> 
> This is due to this code, which takes an XCAR without checking whether the 
> spec is a cons:
> 
>   /* Support (disable-eval PROP) which is used by enriched.el.  */
>   if (CONSP (spec) && EQ (XCAR (spec), Qdisable_eval))
>     {
>       enable_eval = false;
>       spec = XCAR (XCDR (spec));
>     }
> 
> The attached patch fixes this.

Thanks, installed.