[RFC v2 08/20] sysdeps/wait: Use waitid if avaliable

[Florian Weimer]

* Zack Weinberg:

> On Mon, Jun 24, 2019 at 8:12 PM Alistair Francis
> <alistair.francis@wdc.com> wrote:
>>
>> If the waitid syscall is avaliable let's use that as waitpid
>> and wait4 aren't always avaliable (they aren't avaliable on RV32).
>
> wait4 does something that can't be done any other way (retrieve
> resource usage information), RV32 should have it.

I think the problem is that the kernel provides wait4 under a different
name because struct rusage has two fields of struct timeval.

I think this needs to be covered by the syscall renaming mechanism, to
get a working wait4, and not changes to wait.

Thanks,
Florian