Merge r1569615 from trunk:

handle POLLERR/POLLHUP during poll() to avoid high CPU busy loop.

Submitted By: Joffroy Christen <joffroy.christen solvaxis com>, Eric Covener]
Committed By: covener
 

Submitted by: covener
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1570321 13f79535-47bb-0310-9956-ffa450edef68