move container_of to types.h

The container_of macro is useful as a general solution.  It belongs
in types.h, rather than target.h where it was introduced.  Requires
the offsetof macro, which comes from <stddef.h> (moved as well).

src/target/target.h

@@ -26,7 +26,6 @@
 #ifndef TARGET_H
 #define TARGET_H
 
-#include <stddef.h>
 #include "types.h"
 #include "jim.h"
 
@@ -39,18 +38,6 @@ struct mem_param;
 struct reg_param;
 
 
-/**
- * Cast a member of a structure out to the containing structure.
- * @param ptr The pointer to the member.
- * @param type The type of the container struct this is embedded in.
- * @param member The name of the member within the struct.
- *
- * This is a mechanism which is used throughout the Linux kernel.
- */
-#define container_of(ptr, type, member) ({			\
-	const typeof( ((type *)0)->member ) *__mptr = (ptr);	\
-	(type *)( (char *)__mptr - offsetof(type,member) );})
-
 /*
  * TARGET_UNKNOWN = 0: we don't know anything about the target yet
  * TARGET_RUNNING = 1: the target is executing user code