Merge r785661 from trunk:

mod_proxy_http: fix case sensitivity checking transfer encoding
PR 47383 [Ryuzo Yamamoto]


Submitted by: niq
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@791540 13f79535-47bb-0310-9956-ffa450edef68