graphviz: add fails-with-clang comment

Formula/graphviz.rb

@@ -5,15 +5,16 @@ def build_bindings?
 end
 
 class Graphviz < Formula
+  homepage 'http://graphviz.org/'
   url 'http://www.graphviz.org/pub/graphviz/stable/SOURCES/graphviz-2.28.0.tar.gz'
   md5 '8d26c1171f30ca3b1dc1b429f7937e58'
-  homepage 'http://graphviz.org/'
 
   depends_on 'pkg-config' => :build
-
   depends_on 'pango' if ARGV.include? '--with-pangocairo'
   depends_on 'swig' if build_bindings?
 
+  # fails_with_clang
+
   def options
     [["--with-pangocairo", "Build with Pango/Cairo for alternate PDF output"],
      ["--with[out]-bindings", "Build Perl/Python/Ruby/etc. bindings (default on Lion; may not work on earlier systems)"]]