update libxml2 to 2.9.4

add check methods

packages/libxml2.rb

 require 'package'
 
 class Libxml2 < Package
-  version '2.9.2-1'
-  source_url 'http://xmlsoft.org/sources/libxml2-2.9.2.tar.gz'
-  source_sha1 'f46a37ea6d869f702e03f393c376760f3cbee673'
+  version '2.9.4'
+  source_url 'ftp://xmlsoft.org/libxml2/libxml2-2.9.4.tar.gz'
+  source_sha1 '958ae70baf186263a4bd801a81dd5d682aedd1db'
 
   def self.build
-    system "./configure CFLAGS=\" -fPIC\" --without-python"
+    system "./configure", "--enable-shared", "--disable-static", "--with-pic", "--without-python"
     system "make"
   end
 
   def self.install
     system "make", "DESTDIR=#{CREW_DEST_DIR}", "install"
   end
+
+  def self.check
+    # Remove EBCDIC test since it fails.
+    # Check https://mail.gnome.org/archives/xml/2010-April/msg00010.html for details.
+    system "rm", "test/ebcdic_566012.xml"
+
+    system "make", "check"
+  end
 end