LP #1643949: CVE-2016-6225: xbcrypt/xtrabackup encryption is not setting the IV correctly

**Reported in Launchpad by Sergei Glushchenko last update 13-01-2017 09:55:04

xbcrypt is not setting the IV correctly (and thus is not using an IV)
This causes the same ciphertext to be generated across different runs (for the
same message/same key). The IV provides the extra randomness to ensure
that the same ciphertext is not generated across runs