Include ParameterOIDs when preparing statements on new pool connections

ParameterOIDs passed to ConnPool.PrepareEx are used to prepare the statement
on existing connections in the pool. If additional connections are later
created ParameterOIDs are omitted, potentially causing query failures.

conn_pool.go

@@ -341,7 +341,8 @@ func (p *ConnPool) afterConnectionCreated(c *Conn) (*Conn, error) {
 	}
 
 	for _, ps := range p.preparedStatements {
-		if _, err := c.Prepare(ps.Name, ps.SQL); err != nil {
+		opts := &PrepareExOptions{ParameterOIDs: ps.ParameterOIDs}
+		if _, err := c.PrepareEx(context.Background(), ps.Name, ps.SQL, opts); err != nil {
 			c.die(err)
 			return nil, err
 		}