Merge r1675533 from trunk:

mod_log_config: Add %M format to output request duration in milliseconds.


Submitted by: breser
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1677187 13f79535-47bb-0310-9956-ffa450edef68