Merge r580044, r580465 from trunk:

Strip hop-by-hop headers in proxy response


Fix typo in header name "Trailer"

Submitted by: niq
Reviewed by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@582807 13f79535-47bb-0310-9956-ffa450edef68