Add NT_VMCOREDD, AT_MINSIGSTKSZ from Linux 4.18 to elf.h

[Florian Weimer]

On 08/15/2018 06:52 PM, Joseph Myers wrote:
> 2018-08-15  Joseph Myers<joseph@codesourcery.com>
> 
> 	* elf/elf.c (NT_VMCOREDD): New macro.
> 	(AT_MINSIGSTKSZ): Likewise.

I verified that the constants match the kernel settings.  Looks good to me.

As an aside: AT_MINSIGSTKSZ should really be arch-independent because 
x86 needs it as well (the signal stack usage varies wildly there as well).

Thanks,
Florian