func (rs *Rows) initContextClose(ctx, txctx context.Context) {
	if ctx.Done() == nil && (txctx == nil || txctx.Done() == nil) {
		return
	}
	if bypassRowsAwaitDone {
		return
	}
	closectx, cancel := context.WithCancel(ctx)
	rs.cancel = cancel
	go rs.awaitDone(ctx, txctx, closectx)
}

// awaitDone blocks until ctx, txctx, or closectx is canceled.