inotify: make proper use of Python API to get object size.

In older python versions, it was ok to access an object's type by accessing its
ob_type "member". With python 2.6+, the proper way of accessing it is via
Py_TYPE(object). This patch implements the correct call for the inotify
extension. When under python < 2.6, this macro is defined in mercurial's
util.h.

hgext/inotify/linux/_inotify.c

@@ -327,7 +327,7 b' static void event_dealloc(struct event *'
 	Py_XDECREF(evt->cookie);
 	Py_XDECREF(evt->name);
 
-	(*evt->ob_type->tp_free)(evt);
+	Py_TYPE(evt)->tp_free(evt);
 }
 
 static PyObject *event_repr(struct event *evt)