func Getgroups() (gids []int, err error) {
	n, err := getgroups(0, nil)
	if err != nil {
		return nil, err
	}
	if n == 0 {
		return nil, nil
	}
	if n < 0 || n > 1000 {
		return nil, EINVAL
	}
	a := make([]_Gid_t, n)
	n, err = getgroups(n, &a[0])
	if err != nil {
		return nil, err
	}
	gids = make([]int, n)
	for i, v := range a[0:n] {
		gids[i] = int(v)
	}
	return
}
/*
Wrapped

sysnb	getgroups(ngid int, gid *_Gid_t) (n int, err error)
sysnb	setgroups(ngid int, gid *_Gid_t) (err error)
package unix
import (
	"runtime"
	"syscall"
	"unsafe"
)