The original XtraDB (and InnoDB plugin) is shipped as a separate source tree which is copied
into the MySQL source, after which a setup.sh script must be run to move things into place.

Now that XtraDB is part of the MariaDB source tree, this commit fixes these things up once
and for all:

 - New innodb build scripts.
 - Test suite fixes (new tests and patches to existing).
 - Remove files no longer needed due to this.