mpm_event: worker factor vs pollset.

Make sure the worker factor is at least one (w.r.t. WORKER_FACTOR_SCALE), and
use it to size the pollset appropriately (including K-A and lingering close
connections), in addition to the listening sockets.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1819852 13f79535-47bb-0310-9956-ffa450edef68