mod_proxy_http: Don't unescape/escape forward proxied URLs. Just check them.

PR 42592

also add fix to PR42572 to CHANGES (from r563487/r563489)


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@583002 13f79535-47bb-0310-9956-ffa450edef68