Fix Bug: Modify sub file epoll setting if there is a sub file when
doing epoll_ctl modify operation.

Signed-off-by: Xiaofeng Lin <jerrylin.lxf@gmail.com>
Fix Bug: Should change backlog length of the spawned listen socket when
invoking listen on a listen socket.

Signed-off-by: Xiaofeng Lin <jerrylin.lxf@gmail.com>