Add API for static strings, primarily good for identifiers.

Thanks to Konrad Schöbel and Jasper Schulz for helping with the mass-editing.

Modules/_sqlite/cursor.c

@@ -150,8 +150,9 @@ PyObject* _pysqlite_get_converter(PyObject* key)
 {
     PyObject* upcase_key;
     PyObject* retval;
+    _Py_identifier(upper);
 
-    upcase_key = PyObject_CallMethod(key, "upper", "");
+    upcase_key = _PyObject_CallMethodId(key, &PyId_upper, "");
     if (!upcase_key) {
         return NULL;
     }