verbose terminate_handler

[Jason Merrill]

>>>>> "Phil" == Phil Edwards <pedwards@disaster.jaj.com> writes:

>> 3) Add verbose_terminate_handler to libsupc++ or libstdc++ and document it;
>> people would still need to activate it with set_terminate.

> That's got my vote; plus we should put verbose_terminate_handler in the
> extensions namespace (__gnu_cxx).

On further consideration, I think that it makes most sense to put
current_exception_type in the ABI, and verbose_terminate_handler in
libstdc++ somewhere.  But where?  More specifically, where should it be
declared?

Jason