BUG 14037: Add hash function to PyVTKClass type.

In Python 2.7, python was calling PyType_Ready() on the PyVTKClass
type in order to get its superclasses whenever hash() was called.
This raised an exception because this type predates the type/class
refinements that occurred in python 2.2.  A simple fix is to add
tp_hash to the type.

Change-Id: I9f2ec46839bd8409bbc3bfadd3a7ac8791d36ca3

Wrapping/PythonCore/PyVTKClass.cxx

@@ -55,6 +55,17 @@ static PyObject *PyVTKClass_Repr(PyObject *op)
   return PyString_FromString(buf);
 }
 
+//--------------------------------------------------------------------
+static long PyVTKClass_Hash(PyObject *op)
+{
+  size_t y = reinterpret_cast<size_t>(op);
+  y = (y >> 4) | (y << (8 * sizeof(op) - 4));
+  long x = static_cast<long>(y);
+  if (x == -1) { x = -2; }
+
+  return x;
+}
+
 //--------------------------------------------------------------------
 static PyObject *PyVTKClass_Call(PyObject *op, PyObject *arg, PyObject *kw)
 {
@@ -398,7 +409,7 @@ PyTypeObject PyVTKClass_Type = {
   0,                                     // tp_as_number
   0,                                     // tp_as_sequence
   0,                                     // tp_as_mapping
-  0,                                     // tp_hash
+  PyVTKClass_Hash,                       // tp_hash
   PyVTKClass_Call,                       // tp_call
   PyVTKClass_String,                     // tp_string
   PyVTKClass_GetAttr,                    // tp_getattro