Merge the fcgi-proxy-dev branch to trunk, adding a FastCGI back end for

Merge the fcgi-proxy-dev branch to trunk, adding a FastCGI back end for
mod_proxy.  This log message is just a summary of the changes, for the
full original log messages see r357431:393955 in branches/fcgi-proxy-dev.

* modules/proxy/mod_proxy_fcgi.c: New file, holds the impementation of
  our new fcgi backend for mod_proxy.

* modules/proxy/fcgi_protocol.h: New file, holds constants and structures
  for the fcgi protocol.

* modules/proxy/mod_proxy_balancer.c
  (proxy_balancer_canon): Set up r->path_info, so the PATH_INFO env
   variable is correctly passed on to balancer workers.

* modules/proxy/config.m4: Build the new mod_proxy_fcgi module.

* support: Add fcgistarter to svn:ignore.

* support/Makefile.in: Build the new fcgistarter program.

* support/fcgistarter.c: New program, a helper for starting fcgi worker
  processes.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@396063 13f79535-47bb-0310-9956-ffa450edef68