Log Message:
Update percona-toolkit to 2.2.9.

Changes:
* Fixed bug 1258135: pt-deadlock-logger introduces a noise to MySQL
* Fixed bug 1329422: pt-online-schema-change foreign-keys-method=none
  breaks constraints
* Fixed bug 1315130: pt-online-schema-change not properly detecting
  foreign keys
* Fixed bug 1335960: pt-query-digest cannot parse binlogs from 5.6
* Fixed bug 1335322: pt-stalk fails when variable or threshold is
  non-integer