Merge r1570598 from trunk:

Log an error in mod_proxy_http when reading the request body fails.
Follow-up to r1538776 where incomplete bodies are detected and an error returned through the input filters.


Submitted by: ylavic
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1573356 13f79535-47bb-0310-9956-ffa450edef68