Remove unused runc files

We no longer use runc code to read network I/O usage. This lets
us remove a lot of vendored code.

Signed-off-by: Matthew Heon <matthew.heon@gmail.com>

Closes: #425
Approved by: rhatdan

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

@@ -1,44 +0,0 @@
-// +build !windows
-
-package utils
-
-import (
-	"io/ioutil"
-	"os"
-	"strconv"
-
-	"golang.org/x/sys/unix"
-)
-
-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 unix.CloseOnExec
-		unix.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
-}
-
-// NewSockPair returns a new unix socket pair
-func NewSockPair(name string) (parent *os.File, child *os.File, err error) {
-	fds, err := unix.Socketpair(unix.AF_LOCAL, unix.SOCK_STREAM|unix.SOCK_CLOEXEC, 0)
-	if err != nil {
-		return nil, nil, err
-	}
-	return os.NewFile(uintptr(fds[1]), name+"-p"), os.NewFile(uintptr(fds[0]), name+"-c"), nil
-}