[PATCH] AArch64: Add hp-timing.h

[Florian Weimer]

* Szabolcs Nagy via Libc-alpha:

> The 06/28/2021 11:11, Wilco Dijkstra wrote:
>> Add hp-timing.h using the cntcvt_el0 counter. Return timing in nanoseconds
>> so it is fully compatible with generic hp-timing. Don't set HP_TIMING_INLINE
>> in the dynamic linker since very old kernels may not handle cntcvt correctly.
>
> can you please add a comment here that this
> is only used in internal benchmarks and not
> in installed glibc binaries. with that it's
> ok to commit.

This commit would not be entirely accurate.  We install and ship the
benchtests, so they need to use a stable ISA (and kernel ABI).

If the benchtests are like the testsuite and are not intended to be
installed and distributed, we probably need to make downstream changes.

Thanks,
Florian