Change clamav.rb to make it work with zlib 1.2.11

packages/clamav.rb

@@ -3,11 +3,18 @@ require 'package'
 class Clamav < Package
   description 'ClamAV is an open source antivirus engine for detecting trojans, viruses, malware & other malicious threats.'
   homepage 'https://www.clamav.net/'
-  version '0.99.2'
+  version '0.99.2-1'
   source_url 'https://www.clamav.net/downloads/production/clamav-0.99.2.tar.gz'
   source_sha256 '167bd6a13e05ece326b968fdb539b05c2ffcfef6018a274a10aeda85c2c0027a'
 
+  depends_on 'patch'
+  depends_on 'autoconf'
+
   def self.build
+    # Apply patch available at https://bugzilla.clamav.net/show_bug.cgi?id=11711.
+    # This will be fixed in next release.
+    system "curl -L 'https://bugzilla.clamav.net/attachment.cgi?id=7207' | patch -p0"
+    system "autoconf"
     system "./configure"
     system "make"
   end