MINOR: http: Add support for http 413 status

Add 413 http "payload too large" status code. This will allow 413 to be
used in deny_status and errorfile.

(cherry picked from commit 85048f80c9c1ca22732951e83c01ab0b31f5371f)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>

[Cf: A "connection: close" has been added in the HTTP message to be consistent
     with other error codes]

(cherry picked from commit ce7e8f6ead075743603475b3964919c6ec9fb8a3)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
diff --git a/include/common/http.h b/include/common/http.h
index 66114d3..249cd32 100644
--- a/include/common/http.h
+++ b/include/common/http.h
@@ -87,6 +87,7 @@
 	HTTP_ERR_405,
 	HTTP_ERR_408,
 	HTTP_ERR_410,
+	HTTP_ERR_413,
 	HTTP_ERR_421,
 	HTTP_ERR_425,
 	HTTP_ERR_429,