Remove extra src_prepare from MariaDB 5.5.x for bug 462078
Cleanup IUSE="berkdb" and EAPI support.
Drop EAPI 3 as we are now using REQUIRED_USE and all builds are EAPI4+ which use mysql-v2.eclass.
Drop IUSE="berkdb" as only a post-install note affected <5.1 and mysql-v2.eclass only supports 5.1.50+
Prepwork for MySQL 5.7 release.

Signed-off-by: Robin H. Johnson <robbat2@orbis-terrarum.net>
[dev-db/mariadb] Bump to 10.0.2 version.
[dev-db/mariadb] Drop extra src_prepare on mariadb-10.0 - fixes bug 462078.
Bump mysql-cluster to 7.2.8 and fix the old version unpack failure