Add missing files to EXTRA_DIST.

Also delete some unused files.
diff --git a/python/setup.py b/python/setup.py
index 22f6e81..1e71a70 100755
--- a/python/setup.py
+++ b/python/setup.py
@@ -114,7 +114,8 @@
         filepath = os.path.join(dirpath, filename)
         if filepath.endswith("_pb2.py") or filepath.endswith(".pyc") or \
           filepath.endswith(".so") or filepath.endswith(".o") or \
-          filepath.endswith('google/protobuf/compiler/__init__.py'):
+          filepath.endswith('google/protobuf/compiler/__init__.py') or \
+          filepath.endswith('google/protobuf/util/__init__.py'):
           os.remove(filepath)
     # _clean is an old-style class, so super() doesn't work.
     _clean.run(self)
@@ -137,7 +138,7 @@
     GenerateUnittestProtos()
 
     # Make sure google.protobuf/** are valid packages.
-    for path in ['', 'internal/', 'compiler/', 'pyext/']:
+    for path in ['', 'internal/', 'compiler/', 'pyext/', 'util/']:
       try:
         open('google/protobuf/%s__init__.py' % path, 'a').close()
       except EnvironmentError: