[Development] Removing the -c++11 option from configure

[Stephen Kelly]

Thiago Macieira wrote:
> 
> Anything I missed? Opinions?

As far as I know, qmake `CONFIG += c++11` causes 

 -std=c++11

or similar to be used on compile and link lines. For the sake of user code, 
you might want to use 

 -std=gnu++11

instead, because 

 -std=gnu++98

is the default and you turn of extensions by not using it.

 http://thread.gmane.org/gmane.comp.programming.tools.cmake.devel/10214

I don't know if that has any particular benefits for the build of Qt, but 
something to consider while on the topic, and when considering qmake users 
using `CONFIG += c++11` (though I have not seen qmake users complain about 
this).

Thanks,

Steve.