runtime: initialise cpu.HWCap on netbsd/arm64
NetBSD does not supply AT_HWCAP, however we still need to initialise
cpu.HWCaps. For now specify the bare minimum until we add some form of
capabilities detection. See
https://golang.org/issue/30824#issuecomment-
494901591
Follows CL 174129 which did the same for openbsd/arm64.
Updates #30824
Change-Id: I43a86b583bc60d259a66772703de06970124bb7f
Reviewed-on: https://go-review.googlesource.com/c/go/+/257998
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Trust: Benny Siegert <bsiegert@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Benny Siegert <bsiegert@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>