devel/nss is broken on aarch64 (toolchain problem, help needed)

[Tobias Nygren <tnn%NetBSD.org@localhost>]

Hi,

devel/nss is broken when compiling aarch64 crypto accel files.
(aarch64-gcm.c and aes-armv8.c)

There are some mystery errors like these from as(1):

Error: selected processor does not support `aesimc v0.16b,v0.16b'
Error: selected processor does not support `pmull v6.1q,v0.1d,v20.1d'

But the required compiler flag (-march=armv8-a+crypto) is definitely
passed. Is this a problem of too old GCC and/or binutils?
I thought to use devel/binutils/override-as.mk but it seems pkgsrc
binutils is also broken on aarch64 so need to fix that first.

Kind regards,
-Tobias