bpo-39573: Use Py_TYPE() macro in ctypes.h (GH-18411)

Author: corona10

Modules/_ctypes/ctypes.h

@@ -112,12 +112,12 @@ extern int PyObject_stginfo(PyObject *self, Py_ssize_t *psize, Py_ssize_t *palig
 
 
 extern PyTypeObject PyCData_Type;
-#define CDataObject_CheckExact(v)       ((v)->ob_type == &PyCData_Type)
+#define CDataObject_CheckExact(v)       (Py_TYPE(v) == &PyCData_Type)
 #define CDataObject_Check(v)            PyObject_TypeCheck(v, &PyCData_Type)
 #define _CDataObject_HasExternalBuffer(v)  ((v)->b_ptr != (char *)&(v)->b_value)
 
 extern PyTypeObject PyCSimpleType_Type;
-#define PyCSimpleTypeObject_CheckExact(v)       ((v)->ob_type == &PyCSimpleType_Type)
+#define PyCSimpleTypeObject_CheckExact(v)       (Py_TYPE(v) == &PyCSimpleType_Type)
 #define PyCSimpleTypeObject_Check(v)    PyObject_TypeCheck(v, &PyCSimpleType_Type)
 
 extern PyTypeObject PyCField_Type;