Add ptrace functions of job-control and signal

Note that a forked process automatically becomes ptraced state in this
commit.

kernel/host.c

@@ -362,6 +362,7 @@ static int process_msg_prepare_process(unsigned long rphys)
 		return -ENOMEM;
 	}
 	proc->pid = pn->pid;
+	kprintf("prepare_process,pid=%d,ptrace=%08x\n", proc->pid, proc->ftn->ptrace);
 	proc->pgid = pn->pgid;
 	proc->ftn->pid = pn->pid;
 	proc->vm->region.user_start = pn->user_start;