sjlj-exceptions ICE. simplified test case

[Jason Merrill]

>>>>> Geert Bosch <bosch@gnat.com> writes:

 > Actually GNAT currently uses an unwind mechanism for x86 which works by
 > scanning the prologue. This code is well documented and should be easily 
 > adaptable; I would be willing to do the work if people agree that having
 > such an unwinder would be nice.

That would be great as a fallback mechanism, thanks.

Jason