core: Detect incomplete request and response bodies, log an error and
forward it to the underlying filters. 

PR: 55475
Submitted by: Yann Ylavic
Reviewed by: ylavic, wrowe, rpluem
Backports: r1538776


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@1619754 13f79535-47bb-0310-9956-ffa450edef68