[PATCH] aarch64: add support or hwcap3,4

[Florian Weimer]

* 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?

Thanks,
Florian