remove support for missing ANSI C header files (limits.h, stddef.h, etc).
diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
index c897f65..81a65f0 100644
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -247,9 +247,7 @@
 
 #endif
 
-#ifdef HAVE_STDDEF_H
-# include <stddef.h>
-#endif
+#include <stddef.h>
 
 #ifndef offsetof
 # define offsetof(type, member)	((size_t)(&((type *)0)->member))