* Yamada Denki boosted by report to up stake in Best Denki * Asahi Glass sinks, cuts profit forecast on weak demand * Pharmaceuticals in favour, driven by Shionogi drug trial By Sophie Knight TOKYO, July 12 (Reuters) - Japan's Nikkei share average inched down in early trade on Thursday ahead of the outcome of a Bank of Japan policy meeting, with the central bank expected to hold off on further policy easing despite slowing global growth.