vendor: update google/cadvisor and opencontainers/runc

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

vendor/github.com/opencontainers/runc/libcontainer/system/linux.go

@@ -5,26 +5,13 @@ package system
 import (
 	"os"
 	"os/exec"
-	"syscall" // only for exec
+	"sync"
 	"unsafe"
 
 	"github.com/opencontainers/runc/libcontainer/user"
 	"golang.org/x/sys/unix"
 )
 
-// If arg2 is nonzero, set the "child subreaper" attribute of the
-// calling process; if arg2 is zero, unset the attribute.  When a
-// process is marked as a child subreaper, all of the children
-// that it creates, and their descendants, will be marked as
-// having a subreaper.  In effect, a subreaper fulfills the role
-// of init(1) for its descendant processes.  Upon termination of
-// a process that is orphaned (i.e., its immediate parent has
-// already terminated) and marked as having a subreaper, the
-// nearest still living ancestor subreaper will receive a SIGCHLD
-// signal and be able to wait(2) on the process to discover its
-// termination status.
-const PR_SET_CHILD_SUBREAPER = 36
-
 type ParentDeathSignal int
 
 func (p ParentDeathSignal) Restore() error {
@@ -51,7 +38,7 @@ func Execv(cmd string, args []string, env []string) error {
 		return err
 	}
 
-	return syscall.Exec(name, args, env)
+	return unix.Exec(name, args, env)
 }
 
 func Prlimit(pid, resource int, limit unix.Rlimit) error {
@@ -100,15 +87,23 @@ func Setctty() error {
 	return nil
 }
 
+var (
+	inUserNS bool
+	nsOnce   sync.Once
+)
+
 // RunningInUserNS detects whether we are currently running in a user namespace.
 // Originally copied from github.com/lxc/lxd/shared/util.go
 func RunningInUserNS() bool {
-	uidmap, err := user.CurrentProcessUIDMap()
-	if err != nil {
-		// This kernel-provided file only exists if user namespaces are supported
-		return false
-	}
-	return UIDMapInUserNS(uidmap)
+	nsOnce.Do(func() {
+		uidmap, err := user.CurrentProcessUIDMap()
+		if err != nil {
+			// This kernel-provided file only exists if user namespaces are supported
+			return
+		}
+		inUserNS = UIDMapInUserNS(uidmap)
+	})
+	return inUserNS
 }
 
 func UIDMapInUserNS(uidmap []user.IDMap) bool {
@@ -140,7 +135,7 @@ func GetParentNSeuid() int64 {
 
 // SetSubreaper sets the value i as the subreaper setting for the calling process
 func SetSubreaper(i int) error {
-	return unix.Prctl(PR_SET_CHILD_SUBREAPER, uintptr(i), 0, 0, 0)
+	return unix.Prctl(unix.PR_SET_CHILD_SUBREAPER, uintptr(i), 0, 0, 0)
 }
 
 // GetSubreaper returns the subreaper setting for the calling process