Bug fixes

This release fixes:
- Issue #3156924: Error messageWarning: call_user_func_array() expects parameter 1 to be a valid callback, function 'mail_login_extra_validate' not found or invalid function name in Drupal\Core\Form\FormValidator->executeValidateHandlers() (line 82 of core/lib/Drupal/Core/

1) Support to drush 8
2) Fixing error when injecting ContainerBuilder
3) Drupal 9 readiness

Changes since 7.x-3.9:

For drupal 9