app-antivirus/clamav: Revbump to fix various linking issues

app-antivirus/clamav: Revbump to fix various linking issues

- Don't call configure with --with-zlib=/usr or else we end up having
  "-L/usr/lib" in linker flags which breaks 64bit compilations in 17.1
  profiles
- Once again (third time) use pkg-config to check for libxml2 in order
  to avoud automagic and unnecessary linking to dev-libs/icu

Bug: https://bugs.gentoo.org/661328
Closes: https://bugs.gentoo.org/699296
Package-Manager: Portage-2.3.79, Repoman-2.3.18
Signed-off-by: Lars Wendler <polynomial-c@gentoo.org>