Fix the proxy to set r->headers_out when sending responses. Wherever

a header is sent, it is added to headers_out.  This is necessary to
allow things like logging based on outbound headers to work properly.

PR: 569
Obtained from:
Submitted by:
Reviewed by:	Dean Gaudet


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@79039 13f79535-47bb-0310-9956-ffa450edef68