[PATCH] aarch64: add support or hwcap3,4

[enh]

it was pointed out to me when i went to make a matching change in
bionic that there's also some arm documentation that needs updating:
https://github.com/ARM-software/abi-aa/blob/main/sysvabi64/sysvabi64.rst#941gnu-c-library-ifunc-interface

On Tue, Apr 1, 2025 at 12:12 PM Florian Weimer <fweimer@redhat.com> wrote:
>
> * Yury Khrustalev:
>
> > On Tue, Apr 01, 2025 at 04:50:51PM +0200, Florian Weimer wrote:
> >> * Yury Khrustalev:
> >>
> >> > This is just to ensure both hwcap3,4 are usable on AArch64 targets.
> >>
> >> Is there an AT_HWCAP or AT_HWCAP2 bit that indicates the additional
> >> arguments are available?
> >
> > No, there is no such bit.
>
> Ah, right, this is expected to be handled through the _size member.
> Maybe expand the comments in <sys/ifunc.h> a bit to explains this?
>
> Thanks,
> Florian
>