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/Modules/posixmodule.c b/Modules/posixmodule.c
index 7ac7484..f5beb09 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -35,10 +35,10 @@
# include <windows.h>
#endif
-#include "pycore_ceval.h" /* _PyEval_ReInitThreads() */
-#include "pycore_import.h" /* _PyImport_ReInitLock() */
-#include "pycore_pystate.h" /* _PyInterpreterState_GET() */
-#include "structmember.h"
+#include "pycore_ceval.h" // _PyEval_ReInitThreads()
+#include "pycore_import.h" // _PyImport_ReInitLock()
+#include "pycore_pystate.h" // _PyInterpreterState_GET()
+#include "structmember.h" // PyMemberDef
#ifndef MS_WINDOWS
# include "posixmodule.h"
#else