Changes towards exit. Need to fix thread suspend first.

tasks/mm0/include/syscalls.h

@@ -46,6 +46,7 @@ struct sys_shmget_args {
 int sys_shmget(key_t key, int size, int shmflg);
 
 int sys_fork(struct tcb *parent);
+void sys_exit(struct tcb *task, int status);
 
 #endif /* __MM0_SYSARGS_H__ */
 

tasks/mm0/include/utcb.h

@@ -5,6 +5,7 @@
 #include <task.h>
 void *utcb_vaddr_new(void);
 int utcb_pool_init(void);
+int utcb_vaddr_del(void *utcb_addr);
 
 
 /* IPC to send utcb address information to tasks */