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/abstract.c b/Objects/abstract.c
index 8e22dfe..6e390dd 100644
--- a/Objects/abstract.c
+++ b/Objects/abstract.c
@@ -1,12 +1,12 @@
/* Abstract Object Interface (many thanks to Jim Fulton) */
#include "Python.h"
-#include "pycore_abstract.h" // _PyIndex_Check()
-#include "pycore_ceval.h" // _Py_EnterRecursiveCall()
+#include "pycore_abstract.h" // _PyIndex_Check()
+#include "pycore_ceval.h" // _Py_EnterRecursiveCall()
#include "pycore_pyerrors.h"
-#include "pycore_pystate.h" // _PyThreadState_GET()
+#include "pycore_pystate.h" // _PyThreadState_GET()
#include <ctype.h>
-#include "structmember.h" /* we need the offsetof() macro from there */
+#include <stddef.h> // offsetof()
#include "longintrepr.h"