Add depends=[headers] to setup.py

Any modification of a header file now triggers a rebuild of the C
extension module.

Closes: https://github.com/python-ldap/python-ldap/pull/33
Signed-off-by: Christian Heimes <cheimes@redhat.com>

setup.py

@@ -142,6 +142,17 @@ class OpenLDAP2:
         'Modules/options.c',
         'Modules/berval.c',
       ],
+      depends = [
+        'Modules/LDAPObject.h',
+        'Modules/berval.h',
+        'Modules/common.h',
+        'Modules/constants_generated.h',
+        'Modules/constants.h',
+        'Modules/functions.h',
+        'Modules/ldapcontrol.h',
+        'Modules/message.h',
+        'Modules/options.h',
+      ],
       libraries = LDAP_CLASS.libs,
       include_dirs = ['Modules'] + LDAP_CLASS.include_dirs,
       library_dirs = LDAP_CLASS.library_dirs,