bugfix: --echo-hidden is not supported by \sf statements

Hello

this is very simple patch - it enables hidden_queries for commands
\sf and \ef to be consistent with other describing commands.

bash-4.1$ ./psql postgres -E
psql (9.3devel)
Type "help" for help.

postgres=# \sf+ foo
********* QUERY **********
SELECT pg_catalog.pg_get_functiondef(16385)
**************************

CREATE OR REPLACE FUNCTION public.foo(a integer)
RETURNS integer
LANGUAGE plpgsql
1 AS $function$
2 begin
3 return 10/a;
4 end;
5 $function$

Regards

Pavel Stehule