mysql55: 5.5.54 -> 5.5.57 for multiple CVEs

See:
  - https://dev.mysql.com/doc/relnotes/mysql/5.5/en/news-5-5-56.html
  - https://dev.mysql.com/doc/relnotes/mysql/5.5/en/news-5-5-56.html
  - https://dev.mysql.com/doc/relnotes/mysql/5.5/en/news-5-5-55.html
  - http://www.oracle.com/technetwork/security-advisory/cpujul2017-3236622.html

Fixes: CVE-2017-3635 CVE-2017-3636 CVE-2017-3641 CVE-2017-3648 CVE-2017-3651
       CVE-2017-3652 CVE-2017-3653