Add support for reading FCGI_STDOUT and FCGI_END_REQUEST records from the

Add support for reading FCGI_STDOUT and FCGI_END_REQUEST records from the
back end fastcgi process.  This includes switching to a poll based dispatch
loop that handles interleaved reads and writes.

* modules/proxy/mod_proxy_fcgi.c
  (MAX_INPUT_BYTES): Removed, we now use AP_IOBUFSIZE.
  (handle_headers): New helper function for parsing headers out of the
   response data.
  (send_stdin): Removed, code incorporated into dispatch routine.
  (dispatch): New, poll based dispatch loop that handles both reads and
   writes.
  (fcgi_do_request): Call new dispatch routine.  Return OK if we get
   through without errors.

Submitted By: Garrett Rooney <rooneg apache.org>

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/fcgi-proxy-dev@359901 13f79535-47bb-0310-9956-ffa450edef68