In current implementation, the asynchronous call "epoll_ctl()" unable
to wakeup the thread if pending on "epoll_wait()", the newly
added/delete FD cannot be used in the current waiting list,
this patch uses a reserved file object to wake up pending poll internal,
re-traverse the waiting list when a new event comes.
Signed-off-by: chao.an <anchao@xiaomi.com>