* Heineken may boost $6 billion offer for APB – sources * Offer likely, preventing F&N;'s stake sale to Thais – source * APB, F&N; shares suspended (Adds detail on the talks, analyst comments) By Eveline Danubrata and Denny Thomas SINGAPORE/HONG KONG, Aug 17 (Reuters) – Heineken NV, the world's third-biggest brewer, is in […]