bpo-40268: Remove unused structmember.h includes (GH-19530)
If only offsetof() is needed: include stddef.h instead.
When structmember.h is used, add a comment explaining that
PyMemberDef is used.
diff --git a/Objects/descrobject.c b/Objects/descrobject.c
index fe7ba79..572baa5 100644
--- a/Objects/descrobject.c
+++ b/Objects/descrobject.c
@@ -5,7 +5,7 @@
#include "pycore_object.h"
#include "pycore_pystate.h" // _PyThreadState_GET()
#include "pycore_tupleobject.h"
-#include "structmember.h" /* Why is this not included in Python.h? */
+#include "structmember.h" // PyMemberDef
_Py_IDENTIFIER(getattr);