Git commits in Moodle x.x.x by Koen Nys

commit bb9f8451b7c734c80404dda8e5432132438e80b7
Author: Koen Nys <koen.nys@gmail.com>
Date:   Mon, 13 Mar 2017 23:12:31 +0800
Tag:    v3.3.0-beta

MDL-57686 auth/db: added pdo support.