libselinux: fix python audit2why binding error

There is a missing error check in audit2why.c.  Check for error and
return NULL if we can't initialize instead of just pretending it worked.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Dan Walsh <dwalsh@redhat.com>
diff --git a/libselinux/src/audit2why.c b/libselinux/src/audit2why.c
index d48fbeb..43b725c 100644
--- a/libselinux/src/audit2why.c
+++ b/libselinux/src/audit2why.c
@@ -287,8 +287,9 @@
 static PyObject *init(PyObject *self __attribute__((unused)), PyObject *args) {
   int result;
   char *init_path=NULL;
-  if (PyArg_ParseTuple(args,(char *)"|s:policy_init",&init_path)) 
-	  result = __policy_init(init_path);
+  if (!PyArg_ParseTuple(args,(char *)"|s:policy_init",&init_path))
+    return NULL;
+  result = __policy_init(init_path);
   return Py_BuildValue("i", result);
 }