fdo#46926: fix UNO struct comparison in Python 2

This requires setting a rich comparison flag in Python 2, while Python 3
uses rich comparison by default.
(regression from a09ce468)

pyuno/source/module/pyuno.cxx

@@ -641,9 +641,16 @@ static PyObject* PyUNO_cmp( PyObject *self, PyObject *that, int op )
     {
         raisePyExceptionWithAny( makeAny( e ) );
     }
-    return Py_False;
+    return (op == Py_EQ ? Py_False : Py_True);
 }
 
+/* Python 2 has a tp_flags value for rich comparisons.  Python 3 does not (on by default) */
+#ifdef Py_TPFLAGS_HAVE_RICHCOMPARE
+#define TP_FLAGS (Py_TPFLAGS_HAVE_RICHCOMPARE)
+#else
+#define TP_FLAGS 0
+#endif
+
 static PyTypeObject PyUNOType =
 {
     PyVarObject_HEAD_INIT( &PyType_Type, 0 )
@@ -654,7 +661,7 @@ static PyTypeObject PyUNOType =
     (printfunc) 0,
     (getattrfunc) PyUNO_getattr,
     (setattrfunc) PyUNO_setattr,
-    0,
+    (cmpfunc) 0,
     (reprfunc) PyUNO_repr,
     0,
     0,
@@ -665,7 +672,7 @@ static PyTypeObject PyUNOType =
     (getattrofunc)0,
     (setattrofunc)0,
     NULL,
-    0,
+    TP_FLAGS,
     NULL,
     (traverseproc)0,
     (inquiry)0,