Update struct signalfd_siginfo from Linux 4.18

[Florian Weimer]

On 08/16/2018 05:38 PM, Joseph Myers wrote:
> 2018-08-16  Joseph Myers<joseph@codesourcery.com>
> 
> 	* sysdeps/unix/sysv/linux/sys/signalfd.h (struct
> 	signalfd_siginfo): Add ssi_addr_lsb, ssi_syscall, ssi_call_addr
> 	and ssi_arch members.

Looks okay.  Matches kernel commit 76b7f670730e87974f71df9f6129811e2769666e.

Thanks,
Florian