TOAST table created for partitioned tables

Hi.

I used to think that $subject didn't happen, but it actually does and ends
up consuming a fixed 8192 bytes on the disk.

create table p (a int[]) partition by list (a);
CREATE TABLE

select pg_table_size('p');
pg_table_size
---------------
8192
(1 row)

select pg_relation_size(c1.oid) as p_size,
pg_relation_size(c1.reltoastrelid) as p_toast_heap_size,
pg_relation_size(c2.oid) as p_toast_index_size
from pg_class c1, pg_class c2, pg_index i
where c1.relname = 'p' and
c1.reltoastrelid = i.indrelid and
c2.oid = i.indexrelid;
p_size | p_toast_heap_size | p_toast_index_size
--------+-------------------+--------------------
0 | 0 | 8192
(1 row)

I think we should prevent this, a fix for which is implemented by the
attached patch.

Thanks,
Amit