clamav 0.97.8

Also address Homebrew/homebrew#16987.

Formula/clamav.rb

@@ -2,14 +2,19 @@ require 'formula'
 
 class Clamav < Formula
   homepage 'http://www.clamav.net/'
-  url 'http://downloads.sourceforge.net/clamav/clamav-0.97.7.tar.gz'
-  sha1 '9b911c557e0b7b5079de86c65b5d83fa78fadfff'
+  url 'http://downloads.sourceforge.net/clamav/clamav-0.97.8.tar.gz'
+  sha1 '078c0ac2b4e69d27eecd7544a8361abcd859e73c'
+
+  skip_clean 'share'
 
   def install
+    (share/'clamav').mkpath
+
     args = %W{--disable-dependency-tracking
               --prefix=#{prefix}
               --disable-zlib-vcheck
-              --libdir=#{lib}}
+              --libdir=#{lib}
+              --sysconfdir=#{etc}}
     args << "--with-zlib=#{MacOS.sdk_path}/usr" unless MacOS::CLT.installed?
 
     system "./configure", *args