Ensure http2 follows http in the meaning of
  status WRITE (meaning 'in the request processing
  phase' even if still consuming the request body,
  not literally in a 'now writing' state).

  Ensure a number of MPMs and the h2 connection io
  no longer clobber the request status line during
  state-only changes.  While at it, clean up some
  very ugly formatting and unnecessary decoration,
  and avoid the wordy _from_conn() flavor when we
  are not passing a connection_rec.

  Ensure the useragent_ip is only used in the case
  where it has been initialized, fall back on the
  connection's remote_ip if the status is accidently
  updated from an uninitialized request_rec.

Revert to 2.4.1 behavior and null the request and vhost as appropriate.
PR: 59333
Submitted by: wrowe
Reviewed by: wrowe, ylavic, rpluem


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1742179 13f79535-47bb-0310-9956-ffa450edef68