don't add/del the wakeup fd to the event_loop registered fd list.
this fixes the unsafe list which causes a core in list_del() if
xio_ev_loop_stop() is called different thread then the one running that
event_loop.
wakeup_event is now a ONESHOT event so it saves the DELete system call once woken up
ADD the wakeup fd on event_loop init and DEL on close
MOD with ONESHOT to stop
hint event_loop that xio_ev_loop_stop(is_self_thread=1) is called from
within the event_loop callback to do a thread fae notification which is
quicker
Merge pull request #5 from rosenbaumalex/master

don't add/del the wakeup fd to the event_loop registered fd list