SST auth password should not be exposed to 'ps'

Also in the error log:

130712 12:24:22 [Note] WSREP: Running: 'wsrep_sst_xtrabackup --role 'donor' --address '192.168.70.3:4444/xtrabackup_sst' --auth 'sst:secret' --socket '/var/lib/mysql/mysql.sock' --datadir '/var/lib/mysql/' --defaults-file '/etc/my.cnf' --gtid '84da6d43-eb0e-11e2-b856-f2edc1eccf76:0''

Doing it in error log should be trivial, however, doing it for wsrep_sst_xtrabackup requires doing it with setproctitle(3) from libbsd.

a) The joiner doesn't need the sst auth in first place (since auth happens on donor).

b) The donor doesn't need to pass wsrep_sst_xtrabackup the user:password either. The wsrep_sst_common can directly parse the my.cnf file.

c) There already seems to be some masking present with sst_auth_real / wsrep_sst_auth but that doesn't seem to be working.

#b is the easiest fix for this, but also requires fixing in wsrep_sst.cc to not pass user:pass

Since the wsrep_sst_auth option may be provided during
testing/RQG, I will keep the option, instead another option:
wsrep_sst_auth can be added under [sst] (but not under [mysqld]) which can be read by
wsrep_sst_common without that showing up in ps.

I have fixed this in PXC, however, note that innobackupex still shows user/pass in ps output.

To prevent this, you need to pass it user/pass (like always) under [client] in my.cnf (and only there), innobackupex can read it from there.

Refer to https://bazaar.launchpad.net/~percona-core/percona-xtradb-cluster/5.5/revision/401 for more details.

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PXC-1396