Can't use exceptions on non-mainstream targets

[Paolo Bonzini]

Aaron Graham wrote:
> It appears that sjlj exceptions are broken (PRs 19774/25266/28493).
> I'm not sure this is true for _every_ target, but it appears to be
> true for many.

The real bug is PR28493, not PR19774.  The latter (and PR25266 which is 
related) only affect less common cases, i.e. using alloca or 
variable-length arrays.  Unlike PR19774, which is as old as 3.4, PR28493 
is new to 4.1.0 (as you know because you are the reporter).

I think it is low priority only because nobody has yet confirmed it 
(most likely because most GCC developers work on dw2 targets).

Paolo