CLEANUP: epoll: epoll_events should be allocated according to global.tune.maxpollevents

CLEANUP: epoll: epoll_events should be allocated according to global.tune.maxpollevents

Willy: commit f2e8ee2b introduced an optimization in the old speculative epoll
code, which implemented its own event cache. It was needed to store that many
events (it was bound to maxsock/4 btw). Now the event cache lives on its own
and we don't need this anymore. And since events are allocated on the kernel
side, we only need to allocate the events we want to return.

As a result, absmaxevents will be not used anymore. Just remove the definition
and the comment of it, replace it with global.tune.maxpollevents. It is also an
optimization of memory usage for large amounts of sockets.

Signed-off-by: Godbach <nylzhaowei@gmail.com>