backport 946616 and 946617 from trunk:

  PR49308: Header directive doesn't see CGI-issued headers because they live in err_headers.
  emphasize request/response in the timing description, easy to miss the significance


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@946756 13f79535-47bb-0310-9956-ffa450edef68