patch from Stéphane Bidoul to include drv_libxml2.py in setup.py Daniel

* python/setup.py.in: patch from Stéphane Bidoul to include
  drv_libxml2.py in setup.py
Daniel
diff --git a/python/setup.py.in b/python/setup.py.in
index f1c09b0..861d974 100755
--- a/python/setup.py.in
+++ b/python/setup.py.in
@@ -159,7 +159,7 @@
 
 
 descr = "libxml2 package"
-modules = [ 'libxml2' ]
+modules = [ 'libxml2', 'drv_libxml2' ]
 if WITHDLLS:
     modules.append('libxmlmods.__init__')
 c_files = ['libxml2-py.c', 'libxml.c', 'types.c' ]