clamav vulnerability

USN-5233-1 fixed a vulnerability in ClamAV. This update provides
the corresponding update for Ubuntu 14.04 ESM and Ubuntu 16.04 ESM.

Original advisory details:

It was discovered that ClamAV incorrectly handled memory when the
CL_SCAN_GENERAL_COLLECT_METADATA scan option was enabled. A remote attacker
could possibly use this issue to cause ClamAV to crash, resulting in a
denial of service.