Log Message:
Update clamav to 0.99.4 (fixes build)

ClamAV 0.99.4 is a hotfix release to patch a set of vulnerabilities.

- fixes for the following CVE's: CVE-2012-6706, CVE-2017-6419,
  CVE-2017-11423, CVE-2018-0202, and CVE-2018-1000085.
- also included are 2 fixes for file descriptor leaks as well fixes for
  a handful of other important bugs, including patches to support g++ 6, C++11.