[MAJOR] use the new auth framework for http stats

Support the new syntax (http-request allow/deny/auth) in
http stats.

Now it is possible to use the same syntax is the same like in
the frontend/backend http-request access control:
 acl src_nagios src 192.168.66.66
 acl stats_auth_ok http_auth(L1)

 stats http-request allow if src_nagios
 stats http-request allow if stats_auth_ok
 stats http-request auth realm LB

The old syntax is still supported, but now it is emulated
via private acls and an aditional userlist.
diff --git a/include/proto/proto_http.h b/include/proto/proto_http.h
index 68a771e..8213e3b 100644
--- a/include/proto/proto_http.h
+++ b/include/proto/proto_http.h
@@ -81,7 +81,7 @@
 void manage_client_side_cookies(struct session *t, struct buffer *req);
 void manage_server_side_cookies(struct session *t, struct buffer *rtr);
 void check_response_for_cacheability(struct session *t, struct buffer *rtr);
-int stats_check_uri_auth(struct session *t, struct proxy *backend);
+int stats_check_uri(struct session *s, struct proxy *backend);
 void init_proto_http();
 int http_find_header2(const char *name, int len,
 		      char *sol, struct hdr_idx *idx,