[v3] Add __uninitialized_default*; use __is_trivial instead of __is_pod in most places

[Jason Merrill]

On 06/17/2010 04:41 AM, Paolo Carlini wrote:
> Some infrastructure for forthcoming C++0x work + finally got around to
> use __is_trivial instead of the more restrictive __is_pod in many
> places. About the latter in particular, I'm also adding in CC Jason -
> implemented __is_trivial and briefly discussed with him the rather
> straightforward plan of replacing most dispatches in the library based
> on POD-ness to trivial-ness.

Note that I've submitted an NB comment on the FCD suggesting that POD be 
changed from "trivial and standard layout" to "trivially copyable and 
standard layout" to make struct A { const int i; }; POD again.

Jason