catch(...) and forced unwind

[Benjamin Kosnik]

>This one doesn't work, for the reason that Jason gave earlier:
>we've already committed to deleting the exception.  If we want
>to rethrow, then we have to hook into __cxa_end_catch.

Ok. So, just to clarify: 

void __rethrow_cancellation() 
{ 
    // something else
}

might be valid (given sufficient smarts, not given at the moment), or
the whole idea is shot? Keep in mind that the __cancellation_handler is
set once, so it could be used to set the __cxa_end_catch personality to
something that rethrows.

-benjamin