Backports: r1178566

Submitted by: sf
Enforce LimitRequestFieldSize after multiple headers with the same
name have been merged.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x-merge-http-strict@1775699 13f79535-47bb-0310-9956-ffa450edef68