doxymacs: fails_with :clang

Reported upstream, but project looks inactive.

Formula/doxymacs.rb

@@ -5,6 +5,13 @@ class Doxymacs < Formula
   homepage 'http://doxymacs.sourceforge.net/'
   sha1 'b2aafb4f2d20ceb63614c2b9f06d79dd484d8e2e'
 
+  # see http://librelist.com/browser/homebrew/2012/10/14/problems-building-doxymacs-on-mountain-lion/
+  # reported as https://sourceforge.net/tracker/?func=detail&aid=3577208&group_id=23584&atid=378985
+  fails_with :clang do
+    build 421
+    cause "missing symbols while linking"
+  end
+
   def install
     system "./configure", "--disable-debug", "--disable-dependency-tracking",
                           "--prefix=#{prefix}"