X zodb: Kill LastOid from IStorageDriver

There is no such method in zodb/py and this is currently needed only for
NEO storage which which already uses FileStorage directly.

go/neo/client/client.go

@@ -383,11 +383,6 @@ func (c *Client) LastTid(ctx context.Context) (_ zodb.Tid, err error) {
 	return reply.Tid, nil
 }
 
-func (c *Client) LastOid(ctx context.Context) (zodb.Oid, error) {
-	// XXX there is no LastOid in NEO/py
-	panic("TODO")
-}
-
 func (c *Client) Load(ctx context.Context, xid zodb.Xid) (buf *mem.Buf, serial zodb.Tid, err error) {
 	// defer func() ...
 	buf, serial, err = c._Load(ctx, xid)

go/zodb/zodb.go

@@ -197,12 +197,6 @@ type IStorageDriver interface {
 	// If no transactions have been committed yet, LastTid returns 0.
 	LastTid(ctx context.Context) (Tid, error)
 
-	// LastOid returns highest object id of objects committed to storage.
-	//
-	// if there is no data committed yet, LastOid returns Oid zero value	XXX -> better -1 ?
-	// XXX ZODB/py does not define this in IStorage.
-	LastOid(ctx context.Context) (Oid, error)
-
 	// Load loads object data addressed by xid from database.
 	//
 	// Returned are: