c++0x tests fixes

[Jonathan Wakely]

On 29 November 2010 21:45, Paolo Carlini wrote:
>> If so I think I will introduce a dg-require-no-experimental-mode to
>> ignore those tests in this mode.
> Seems a bit overkill to me.

Whether it's overkill or not, I don't like the name - it's a feature
of C++0x, not the fact the implementation is experimental.   When the
C++0x mode is finished and renamed to C++11 mode (or whatever) those
container still won't be able to be instantiated with non-default
constructible types.