build: avoid python 2.4 build failure

I'm not sure when Py_ssize_t was introduced; but Fedora 14 Python 2.7
has it, while RHEL 5 Python 2.4 lacks it.  It should be easy enough
to adjust if someone runs into problems.

* python/typewrappers.h (Py_ssize_t): Define for older python.

python/typewrappers.h

 /*
  * libvirt_wrap.h: type wrappers for libvir python bindings
  *
- * Copyright (C) 2005 Red Hat, Inc.
+ * Copyright (C) 2005, 2011 Red Hat, Inc.
  *
  * Daniel Veillard <veillard@redhat.com>
  */
@@ -21,6 +21,11 @@
 # define ATTRIBUTE_UNUSED
 #endif
 
+/* Work around really old python.  */
+#if PY_MAJOR_VERSION == 2 && PY_MINOR_VERSION < 7
+typedef ssize_t Py_ssize_t;
+#endif
+
 #define PyvirConnect_Get(v) (((v) == Py_None) ? NULL : \
         (((PyvirConnect_Object *)(v))->obj))