C++ compilation fix

Cython/Utility/ObjectHandling.c

@@ -250,14 +250,14 @@ static PyObject *__Pyx_PyDict_GetItem(PyObject *d, PyObject* key) {
 #define __Pyx_GetItemInt(o, i, type, is_signed, to_py_func, is_list, wraparound, boundscheck) \
     (__Pyx_fits_Py_ssize_t(i, type, is_signed) ? \
     __Pyx_GetItemInt_Fast(o, (Py_ssize_t)i, is_list, wraparound, boundscheck) : \
-    (is_list ? (PyErr_SetString(PyExc_IndexError, "list index out of range"), NULL) : \
+    (is_list ? (PyErr_SetString(PyExc_IndexError, "list index out of range"), (PyObject*)NULL) : \
                __Pyx_GetItemInt_Generic(o, to_py_func(i))))
 
 {{for type in ['List', 'Tuple']}}
 #define __Pyx_GetItemInt_{{type}}(o, i, type, is_signed, to_py_func, is_list, wraparound, boundscheck) \
     (__Pyx_fits_Py_ssize_t(i, type, is_signed) ? \
     __Pyx_GetItemInt_{{type}}_Fast(o, (Py_ssize_t)i, wraparound, boundscheck) : \
-    (PyErr_SetString(PyExc_IndexError, "{{ type.lower() }} index out of range"), NULL))
+    (PyErr_SetString(PyExc_IndexError, "{{ type.lower() }} index out of range"), (PyObject*)NULL))
 
 static CYTHON_INLINE PyObject *__Pyx_GetItemInt_{{type}}_Fast(PyObject *o, Py_ssize_t i,
                                                               int wraparound, int boundscheck);