core: Avoid a possible truncation of the faulty header included in the

HTML response when LimitRequestFieldSize is reached.

Submitted by: ylavic
Backports: 1683123
Reviewed by: jailletc36, ylavic, covener




git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1689961 13f79535-47bb-0310-9956-ffa450edef68