Merge r1617018 from trunk:

PR56832 -- mod_ratelimit reports at ERROR level everytime a lower-level filter
encounters an error. Since the core output filter only emits TRACE1, a higher
level filter shouldn't log the same condition as ERROR.


Submitted by: covener
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1622708 13f79535-47bb-0310-9956-ffa450edef68