Merge r732414 from trunk:

As jorton discovered, recent Linux kernels have a new tunable
setting for epoll that will trip up many prefork users.  Write
a log message instead of crashing.

As rpluem notes, some Apache doc is in order.

PR: 46467
Submitted by: trawick
Reviewed by: rpluem, covener, trawick


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@733698 13f79535-47bb-0310-9956-ffa450edef68