[LyX/master] Do not protect \\ as of LaTeX 2021/06/01

[Jean-Marc Lasgouttes]

Le 27/12/2021 à 16:03, Juergen Spitzmueller a écrit :
> +	bool const fragile = LaTeXFeatures::isAvailable("LaTeX-2021/06/01") ?
> +		false : os.fragile();

Maybe this form?
 > +	bool const fragile = os.fragile() && ! 
LaTeXFeatures::isAvailable("LaTeX-2021/06/01");

JMarc