Basic exception guarantee testcases (redux)

[Benjamin Kosnik]

>I've added another 10 tests to vector_ctor.cc locally so perhaps I better 
>just give you a new patch.  Would you like the new files 
>(testsuite_allocator.*) as well or just pull them in from the previous 
>post(s), since they haven't changed?

Please send me a complete patch, with the new and old bits integrated,
and I'll do this today.

thanks,
benjamin