Merge r327185 from trunk:

* Fix PR37100 (SEGV in mod_proxy_ajp), by sending the data up the filter
  chain immediately instead of spooling it completely before passing it
  to the filter chain. It contains a bandaid to handle intentional
  flushes from Tomcat side. Further explanation in code and report.

  ajp.h:           Add ajp_msg_reuse prototype

  mod_proxy_ajp.c: Adjust logic of ap_proxy_ajp_request

  ajp_msg.c:       Add ajp_msg_reuse

  ajp_header.c:    Adjusting logic of ajp_read_header


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@328467 13f79535-47bb-0310-9956-ffa450edef68