Handle reading fastcgi records with content length larger than AP_IOBUFSIZE.

* modules/proxy/mod_proxy_fcgi.c
  (proxy_fcgi_baton_t): New struct, holds per-connection data.
  (dispatch): Set buckets aside into the scratch pool in the baton,
   clearing it when we pass the baton on.  Deal with the case where
   the content length is larger than AP_IOBUFSIZE.  Consistently use
   sizeof when referring to the length of buffers.  Explicitly null
   terminate the read buffer after reading.  Read the padding bytes
   in a second pass to simplify logic.
  (proxy_fcgi_handler): Create our baton and stash it in the connection's
   data member.

Submitted By: Garrett Rooney <rooneg apache.org>


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/fcgi-proxy-dev@360164 13f79535-47bb-0310-9956-ffa450edef68