fork: Skip setting TIF_SIGPENDING in ptrace_init_task

The code in calculate_sigpending will now handle this so
it is just redundant and possibly a little confusing
to continue setting TIF_SIGPENDING in ptrace_init_task.
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

include/linux/ptrace.h

@@ -214,8 +214,6 @@ static inline void ptrace_init_task(struct task_struct *child, bool ptrace)
 			task_set_jobctl_pending(child, JOBCTL_TRAP_STOP);
 		else
 			sigaddset(&child->pending.signal, SIGSTOP);
-
-		set_tsk_thread_flag(child, TIF_SIGPENDING);
 	}
 	else
 		child->ptracer_cred = NULL;