mariadb security and bug fix update

1:5.5.56-2 - Do not fix context and change owner if run by root in mariadb-prepare-db-dir Related: 1458940 - Check properly that datadir includes only expected files Related: 1356897 1:5.5.56-1 - Rebase to 5.5.56 That release also fixes the following security issues: CVE-2016-5617/CVE-2016-6664...