[wwwdocs] Describe behavior of -flifetime-dse in class constructors

[Jakub Jelinek]

On Wed, Feb 17, 2016 at 03:21:07PM +0100, Martin Liška wrote:
> --- htdocs/gcc-6/porting_to.html	14 Feb 2016 13:13:43 -0000	1.14
> +++ htdocs/gcc-6/porting_to.html	17 Feb 2016 14:20:13 -0000
> @@ -324,6 +324,52 @@
>  <tt>-fabi-version</tt> or <tt>-Wabi</tt> option to disable or warn about.
>  </p>
>  
> +<h3>More aggressive optimization of <code>-flifetime-dse</code></h3>
> +
> +<p>
> +The C++ compiler (with enabled <code>-flifetime-dse</code>)
> +has been more aggressive in dead-store elimination in situations where

"has been" looks weird.  I'd say that the C++ compiler is now more
aggressive...

	Jakub