*: fmt.Errorf: use %w when appropriate

This should result in no change when the error is printed, but make the
errors returned unwrappable, meaning errors.As and errors.Is will work.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

libcontainer/intelrdt/intelrdt.go

@@ -414,7 +414,7 @@ func writeFile(dir, file, data string) error {
 		return fmt.Errorf("no such directory for %s", file)
 	}
 	if err := ioutil.WriteFile(filepath.Join(dir, file), []byte(data+"\n"), 0o600); err != nil {
-		return fmt.Errorf("failed to write %v: %v", data, err)
+		return fmt.Errorf("failed to write %v: %w", data, err)
 	}
 	return nil
 }
@@ -521,7 +521,7 @@ func WriteIntelRdtTasks(dir string, pid int) error {
 	// Don't attach any pid if -1 is specified as a pid
 	if pid != -1 {
 		if err := ioutil.WriteFile(filepath.Join(dir, IntelRdtTasks), []byte(strconv.Itoa(pid)), 0o600); err != nil {
-			return fmt.Errorf("failed to write %v: %v", pid, err)
+			return fmt.Errorf("failed to write %v: %w", pid, err)
 		}
 	}
 	return nil