Be more careful about int vs. Oid in ecpglib.

Be more careful about int vs. Oid in ecpglib.

Print an OID value inserted into a SQL query with %u not %d.
The existing code accidentally fails to malfunction when
given an OID above 2^31, but only accidentally; future changes
to our SQL parser could perhaps break it.

Declare the Oid values that ecpg_type_infocache_push() and
ecpg_is_type_an_array() work with as "Oid" not "int".
This doesn't have any functional effect, but it's clearer.

At the moment I don't see a need to back-patch this.

Bug: #19429
Author: fairyfar@msn.com
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/19429-aead3b1874be1a99@postgresql.org