[libstdc++ PATCH, doc], refresh the C++11 implementation statuses to reflect the real status of constexpr

[Jonathan Wakely]

On 16/01/15 13:01 +0200, Ville Voutilainen wrote:
>Duration, complex, char_traits and the random engines are already
>properly constexprified in the library implementation.
>
>I haven't built the manual with these changes. :)

No problem, you need a load of docbook and TeX packages installed.
I'll regenerate the HTML pages some time during stage4.

> Also, I don't know
>how doc patches
>are usually submitted, so please be gentle. :P

They're usually submitted exactly like this - thanks, and thanks for
checking the status of the status table.

I'll commit this soon.