ext/mt_alloc.h

[Benjamin Kosnik]

>> My and Ola's FSF assignments are now near completion (we have sent back 
>> signed assignment papers last week).

These assignments are now ready to go. This code can be integrated.
(Gwain's assignment is still in progress.)

I'm still in favor of moving extra things out of namespace std in
stl_alloc.h and into ext. Does anybody have strong feelings about this?
Another issue is to try and extend GLIBCPP_FORCE_NEW into someting like
GLIBCPP_SELECT_ALLOCATOR. Thoughts?

-benjamin