BUG/MINOR: epoll: use a fix maxevents argument in epoll_wait()

BUG/MINOR: epoll: use a fix maxevents argument in epoll_wait()

epoll_wait() takes a number of returned events, not the number of
fds to consider. We must not pass it the number of the smallest fd,
as it leads to value zero being used, which is invalid in epoll_wait().
The effect may sometimes be observed with peers sections trying to
connect and causing 2-seconds CPU loops upon a soft reload because
epoll_wait() immediately returns -1 EINVAL instead of waiting for the
timeout to happen.

This fix should be backported to 1.4 too (into ev_epoll and ev_sepoll).