mod_proxy: use the original (non absolute) form of the request-line's URI

for requests embedded in CONNECT payloads used to connect SSL backends via
a ProxyRemote forward-proxy. PR 55892.

Submitted by: Hendrik Harms <hendrik.harms gmail com>
Reviewed  by: wrowe, ylavic
Committed by: ylavic


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1665215 13f79535-47bb-0310-9956-ffa450edef68