[Bug libstdc++/54025] atomic won't compile: chrono::duration::duration() is not C++11 compliant

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54025

--- Comment #7 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-07-19 
12:08:29 UTC ---
(In reply to comment #6)
> I think that test is wrong, a duration is only constexpr_default_constructible
> if the rep type has a default-constructor

... that initializes all its members.