use err_headers_out for setting cookies instead of headers_out, so they...

use err_headers_out for setting cookies instead of headers_out, so they persist on non-2xx/3xx statuses (Thanks to Joe Schaefer for this)

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1567434 13f79535-47bb-0310-9956-ffa450edef68