security/clamav: update to 0.100.2.

• Update to 0.100.2
  • Reference: https://blog.clamav.net/2018/10/clamav-01002-has-been-released.html
  • Security: CVE-2018-14680, CVE-2018-14681, CVE-2018-14682, CVE-2018-15378
• Add gnome to USES to fix developer mode warning.

PR: 231925
Submitted by: yasu@utahime.org
Security: CVE-2018-14680, CVE-2018-14681, CVE-2018-14682, CVE-2018-15378