[wwwdocs] Mention libstdc++-v3 <regex> in 4.9 changes.html

[Paolo Carlini]

On 10/02/2013 12:59 PM, Jakub Jelinek wrote:
> We have announced only core language feature completeness, the library 
> was known to be incomplete. And, I think for 4.9 the library C++11 
> support is still meant to be experimental because of the ABI issues, 
> where we know we'll need to change std::string, std::list etc., but 
> are waiting for Dodji's ABI verification stuff before we are confident 
> we can do all those changes safely. Jakub 
That's a good point. But then both the announcement should be *much* 
more explicit that it only talks about the C++ front-end, not library 
(IMHO certainly isn't, and that's a rather serious issue) and 
c++0x_warning.h should be much more explicit that it refers to the 
library, not the front-end, as regards the experimental bit.

Paolo.