The use of the xtrabackup and xtrabackup-v2 methods for SST
has been declared obsolete since version 10.2, now it cannot
be used because of the different redo log format. Accordingly,
we need to remove the xtrabackup-related scripts and dynamically
replace the call to xtrabackup[-v2] to the mariabackup (with a
corresponding warning in the log) when the server performs SST.
https://jira.mariadb.org/browse/MDEV-17835
Merged lp:maria/maria-10.0-galera up to revision 3879.
Added a new functions to handler API to forcefully abort_transaction,
producing fake_trx_id, get_checkpoint and set_checkpoint for XA. These
were added for future possiblity to add more storage engines that
could use galera replication.
