gh-111789: Simplify the sqlite code (GH-111829)

Use new C API functions PyDict_GetItemRef() and
PyMapping_GetOptionalItemString().

Modules/_sqlite/cursor.c

@@ -721,7 +721,6 @@ bind_parameters(pysqlite_state *state, pysqlite_Statement *self,
  } else if (PyDict_Check(parameters)) {
  /* parameters passed as dictionary */
  for (i = 1; i <= num_params_needed; i++) {
- PyObject *binding_name_obj;
  Py_BEGIN_ALLOW_THREADS
  binding_name = sqlite3_bind_parameter_name(self->st, i);
  Py_END_ALLOW_THREADS
@@ -733,17 +732,8 @@ bind_parameters(pysqlite_state *state, pysqlite_Statement *self,
  }
 
  binding_name++; /* skip first char (the colon) */
- binding_name_obj = PyUnicode_FromString(binding_name);
- if (!binding_name_obj) {
- return;
- }
- if (PyDict_CheckExact(parameters)) {
- PyObject *item = PyDict_GetItemWithError(parameters, binding_name_obj);
- current_param = Py_XNewRef(item);
- } else {
- current_param = PyObject_GetItem(parameters, binding_name_obj);
- }
- Py_DECREF(binding_name_obj);
+ PyObject *current_param;
+ (void)PyMapping_GetOptionalItemString(parameters, binding_name, &current_param);
  if (!current_param) {
  if (!PyErr_Occurred() || PyErr_ExceptionMatches(PyExc_LookupError)) {
  PyErr_Format(state->ProgrammingError,

Modules/_sqlite/microprotocols.c

@@ -85,17 +85,16 @@ pysqlite_microprotocols_adapt(pysqlite_state *state, PyObject *obj,
  if (!key) {
  return NULL;
  }
- adapter = PyDict_GetItemWithError(state->psyco_adapters, key);
+ if (PyDict_GetItemRef(state->psyco_adapters, key, &adapter) < 0) {
+ Py_DECREF(key);
+ return NULL;
+ }
  Py_DECREF(key);
  if (adapter) {
- Py_INCREF(adapter);
  adapted = PyObject_CallOneArg(adapter, obj);
  Py_DECREF(adapter);
  return adapted;
  }
- if (PyErr_Occurred()) {
- return NULL;
- }
 
  /* try to have the protocol adapt this object */
  if (PyObject_GetOptionalAttr(proto, state->str___adapt__, &adapter) < 0) {