golang timestub2 代码
文件路径：/src/runtime/timestub2.go
/ Copyright 2018 The Go Authors. All rights reserved.
/ Use of this source code is governed by a BSD-style
/ license that can be found in the LICENSE file.
/go:build !aix && !darwin && !freebsd && !openbsd && !solaris && !windows && !(linux && amd64)
package runtime
func walltime() (sec int64, nsec int32)