views_language_list() has been moved to a class method

The function views_language_list(), which was formerly in the views.module file, has been removed.

In its place, there is
\Drupal\views\Plugin\views\PluginBase::listLanguages()
which is available on any Views plugin that inherits this class.

Example usage:

// Simple call to list languages on a Views plugin -- lists only actual languages... Was:
$languages = views_language_list();
// Now:
$languages = $this->listLanguages();
// More complex call to list languages and include "special" languages
// like Site Default and Selected Content Language... Was:
$languages = array(
    '***CURRENT_LANGUAGE***' => t("Current user's language"),
    '***DEFAULT_LANGUAGE***' => t("Default site language"),
    LanguageInterface::LANGCODE_NOT_SPECIFIED => t('Language neutral'),
);
$languages = array_merge($languages, views_language_list());
// Now:
$languages = $this->listLanguages(LanguageInterface::STATE_ALL | 
    LanguageInterface::STATE_SITE_DEFAULT | PluginBase::INCLUDE_NEGOTIATED);

Note that the language codes for special languages have also changed -- change notice: https://www.drupal.org/node/2328581