Change the FastCGI URL scheme to fcgi://.

* modules/proxy/mod_proxy_fcgi.c
  (proxy_fcgi_canon): Stop pretending unix domain sockets will need their
   own url scheme.
  (FCGI_SCHEME): New constant to describe the FastCGI proxy backend.
  (proxy_fcgi_handler): Drop the fcgi-local stuff, use FCGI_SCHEME now that
   we aren't worrying about multiple types of FastCGI workers.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/fcgi-proxy-dev@367906 13f79535-47bb-0310-9956-ffa450edef68