innobackupex does not raise exceptions on bad args

[Chris Shumake]

Running "innobackupex --badarg" should fail with an error code and a STDERR complaint. It does not.

[Jericho Rivera (jericho-rivera)]

innobackupex --user=root --password='' --badarg=1 /root/backups
161214 00:27:02 innobackupex: Starting the backup operation

IMPORTANT: Please check that the backup run completes successfully.
           At the end of a successful backup run innobackupex
           prints "completed OK!".

161214 00:27:02 version_check Connecting to MySQL server with DSN 'dbi:mysql:;mysql_read_default_group=xtrabackup;mysql_socket=/var/lib/mysql/mysql.sock' as 'root' (using password: NO).
161214 00:27:02 version_check Connected to MySQL server
161214 00:27:02 version_check Executing a version check against the server...
161214 00:27:02 version_check Done.
161214 00:27:02 Connecting to MySQL server host: localhost, user: root, password: set, port: 0, socket: /var/lib/mysql/mysql.sock
Using server version 5.6.34-79.1
innobackupex version 2.3.6 based on MySQL server 5.6.24 Linux (x86_64) (revision id: 7686bfc)
...
161214 00:27:04 Backup created in directory '/root/backups/2016-12-14_00-27-02'
161214 00:27:04 [00] Writing backup-my.cnf
161214 00:27:04 [00] ...done
161214 00:27:04 [00] Writing xtrabackup_info
161214 00:27:04 [00] ...done
xtrabackup: Transaction log of lsn (1632016) to (1632016) was copied.
161214 00:27:04 completed OK!