Added container_of(). This seems about the best place to put it, since

the definition of it uses offsetof(), and the two concepts are related.

src/include/stddef.h

 #define STDDEF_H
 
 /* for size_t */
-#include "stdint.h"
+#include <stdint.h>
 
 #undef NULL
-#define NULL	((void *)0)
+#define NULL ((void *)0)
 
 #undef offsetof
 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
 
+#undef container_of
+#define container_of(ptr, type, member) ({                      \
+	const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
+	(type *)( (char *)__mptr - offsetof(type,member) );})
+
 #endif /* STDDEF_H */