bpo-39573: Use Py_TYPE() macro in Modules directory (GH-18393)

Replace direct access to PyObject.ob_type with Py_TYPE().
diff --git a/Modules/cjkcodecs/multibytecodec.c b/Modules/cjkcodecs/multibytecodec.c
index f24ec93..2dd63a9 100644
--- a/Modules/cjkcodecs/multibytecodec.c
+++ b/Modules/cjkcodecs/multibytecodec.c
@@ -1450,7 +1450,7 @@
             PyErr_Format(PyExc_TypeError,
                          "stream function returned a "
                          "non-bytes object (%.100s)",
-                         cres->ob_type->tp_name);
+                         Py_TYPE(cres)->tp_name);
             goto errorexit;
         }
 
diff --git a/Modules/cjkcodecs/multibytecodec.h b/Modules/cjkcodecs/multibytecodec.h
index 6d34534..94670ec 100644
--- a/Modules/cjkcodecs/multibytecodec.h
+++ b/Modules/cjkcodecs/multibytecodec.h
@@ -65,7 +65,7 @@
     MultibyteCodec *codec;
 } MultibyteCodecObject;
 
-#define MultibyteCodec_Check(op) ((op)->ob_type == &MultibyteCodec_Type)
+#define MultibyteCodec_Check(op) (Py_TYPE(op) == &MultibyteCodec_Type)
 
 #define _MultibyteStatefulCodec_HEAD            \
     PyObject_HEAD                               \