list: use Info(), fix race with delete

Since commit 551629417 we can (and should) use Info() to get access to
file stat. Do this.

While going over directory entries, a parallel runc delete can remove
an entry, and with the current code it results in a fatal error (which
was not observed in practice, but looks quite possible). To fix,
add a special case to continue on ErrNotExist.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
(cherry picked from commit 1a3ee4966c)
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

list.go

@@ -130,8 +130,12 @@ func getContainers(context *cli.Context) ([]containerState, error) {
 		if !item.IsDir() {
 			continue
 		}
-		st, err := os.Stat(filepath.Join(absRoot, item.Name()))
+		st, err := item.Info()
 		if err != nil {
+			if errors.Is(err, os.ErrNotExist) {
+				// Possible race with runc delete.
+				continue
+			}
 			fatal(err)
 		}
 		// This cast is safe on Linux.