[PATCH v2 1/2] setjmp: Use BSD sematic as default for setjmp

[Florian Weimer]

* Adhemerval Zanella:

> POSIX relaxed the relation of setjmp/longjmp and the signal mask
> save/restore, meaning that setjmp does not require to be routed to
> _setjmp to be standard compliant.
>
> This is done to avoid breakage of SIGABRT handlers, since to fully
> make abort AS-safe, it is required to remove the recurisve lock
> used to unblock SIGABRT prior raised the signal.
>
> Also, it allows caller to actually use setjmp, since from
> 7011c2622fe3e10a29dbe74f06aaebd07710127d the symbol is unconditionally
> routed to _setjmp.

I still think we shouldn't do this due to the performance implications.

Thanks,
Florian