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