Parses an array into a valid, rawurlencoded query string.
as of Drupal 8.0. Use Drupal::urlGenerator()->httpBuildQuery() instead.
\Drupal\Core\Routing\PathBasedGeneratorInterface::httpBuildQuery()
function drupal_http_build_query(array $query, $parent = '') {
return Drupal::urlGenerator()
->httpBuildQuery($query, $parent);
}