dev-db/percona-server-5.6.30.76.3 is available since 2016-05-25: https://www.percona.com/doc/percona-server/5.6/release-notes/Percona-Server-5.6.30-76.3.html I copied percona-server-5.6.29.76.2.ebuild over to my overlay. It passed full test suite (aside from bug 584880 which isn't new) on my systems.
Done