[PATCH v4 4/4] posix: Add _Fork [BZ #4737]

[Florian Weimer]

* Adhemerval Zanella:

> For returns_twice we have __attribute_returns_twice__, but I think we might
> want to add it on multiple symbols (not only on _Fork). So I haven't it added
> for now.

I was wondering if gcc knows about these functions.  It does actually
for fork, but it uses that only for gcov as far as I can see.

> Below it is an updated patch based on your comments, is this one ok to
> commit?

This patch looks reasonable to me.

Thanks,
Florian