runtime: fast clock_gettime on FreeBSD, use physical/virtual ARM timer
as setup by the kernel on GOARCH=arm64.
Update #50947
Change-Id: I2f44be9b36e9ce8d264eccc0aa3df10825c5f4f9
Reviewed-on: https://go-review.googlesource.com/c/go/+/422977
Reviewed-by: Heschi Kreinick <heschi@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Meng Zhuo <mzh@golangcn.org>
Reviewed-by: Dmitri Goutnik <dgoutnik@gmail.com>
Run-TryBot: Yuval Pavel Zholkover <paulzhol@gmail.com>