New UTCB implementation almost working.

- KIP's pointer to UTCB seems to work with existing l4lib ipc functions.
- Works up to clone()
- In clone we mmap() the same UTCB on each new thread - excessive.
- Generally during page fault handling, cloned threads may fault on the same page
  multiple times even though a single handling would be enough for all of them.
  Need to detect and handle this.

include/l4/generic/tcb.h

@@ -72,8 +72,7 @@ struct ktcb {
 	struct list_head task_list; /* Global task list. */
 
 	/* UTCB related, see utcb.txt in docs */
-	unsigned long utcb_virt;	/* Virtual ref to task's utcb area */
-	unsigned long utcb_phys;	/* Physical ref to task's utcb area */
+	unsigned long utcb_address;	/* Virtual ref to task's utcb area */
 
 	/* Thread times */
 	u32 kernel_time;	/* Ticks spent in kernel */
@@ -151,5 +150,7 @@ extern struct id_pool *thread_id_pool;
 extern struct id_pool *space_id_pool;
 extern struct id_pool *tgroup_id_pool;
 
+void task_update_utcb(struct ktcb *cur, struct ktcb *next);
+
 #endif /* __TCB_H__ */