Updates Percona Server 5.6 work with OS X 10.9/mavericks

Just a port of the MySQL 5.6 patch in mysql.rb.

Per mysql-related discussions here: 
https://github.com/mxcl/homebrew/issues/23098

and commit here:
https://github.com/mxcl/homebrew/commit/aad5d93f4fabbf69766deb83780d3a6eeab7061a