Revert "Switch to new vendor directory layout"

This reverts commit d5742209d3.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

vendor/github.com/opencontainers/runc/libcontainer/utils/utils_unix.go

@@ -1,33 +0,0 @@
-// +build !windows
-
-package utils
-
-import (
-	"io/ioutil"
-	"strconv"
-	"syscall"
-)
-
-func CloseExecFrom(minFd int) error {
-	fdList, err := ioutil.ReadDir("/proc/self/fd")
-	if err != nil {
-		return err
-	}
-	for _, fi := range fdList {
-		fd, err := strconv.Atoi(fi.Name())
-		if err != nil {
-			// ignore non-numeric file names
-			continue
-		}
-
-		if fd < minFd {
-			// ignore descriptors lower than our specified minimum
-			continue
-		}
-
-		// intentionally ignore errors from syscall.CloseOnExec
-		syscall.CloseOnExec(fd)
-		// the cases where this might fail are basically file descriptors that have already been closed (including and especially the one that was created when ioutil.ReadDir did the "opendir" syscall)
-	}
-	return nil
-}