bpo-40268: Add _PyInterpreterState_GetConfig() (GH-19492)

Don't access PyInterpreterState.config member directly anymore, but
use new functions:

* _PyInterpreterState_GetConfig()
* _PyInterpreterState_SetConfig()
* _Py_GetConfig()
diff --git a/Objects/bytearrayobject.c b/Objects/bytearrayobject.c
index 7ebfa1f..4d1ddec 100644
--- a/Objects/bytearrayobject.c
+++ b/Objects/bytearrayobject.c
@@ -6,7 +6,6 @@
 #include "pycore_bytes_methods.h"
 #include "pycore_object.h"
 #include "pycore_pymem.h"
-#include "pycore_pystate.h"
 #include "structmember.h"
 #include "bytesobject.h"
 #include "pystrhex.h"
@@ -997,8 +996,7 @@
 static PyObject *
 bytearray_str(PyObject *op)
 {
-    PyConfig *config = &_PyInterpreterState_GET_UNSAFE()->config;
-    if (config->bytes_warning) {
+    if (_Py_GetConfig()->bytes_warning) {
         if (PyErr_WarnEx(PyExc_BytesWarning,
                          "str() on a bytearray instance", 1)) {
                 return NULL;
@@ -1023,8 +1021,7 @@
     if (rc < 0)
         return NULL;
     if (rc) {
-        PyConfig *config = &_PyInterpreterState_GET_UNSAFE()->config;
-        if (config->bytes_warning && (op == Py_EQ || op == Py_NE)) {
+        if (_Py_GetConfig()->bytes_warning && (op == Py_EQ || op == Py_NE)) {
             if (PyErr_WarnEx(PyExc_BytesWarning,
                             "Comparison between bytearray and string", 1))
                 return NULL;