cpu: use IsProcessorFeaturePresent to calculate ARM64 on windows

For golang/go#76791

Change-Id: I9500b38b17b5e3e141df8770d82c725c2ba8fd65
Cq-Include-Trybots: luci.golang.try:x_sys-gotip-windows-arm64
Reviewed-on: https://go-review.googlesource.com/c/sys/+/740880
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Quim Muntal <quimmuntal@gmail.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>