BANGKOK, Jan 20 (Reuters) - Southeast Asian stock markets fell in line with global equities on Wednesday, with Singapore posting its worst drop in nearly five months and the Philippines sliding to a near two-year closing low, as energy shares faced pressure due to a relentless slide in oil prices. Singapore's key Straits Times Index ended down 3 percent, its biggest single-day percentage decline since Aug. 24. The Philippine composite index lost 1.5 percent to close at its lowest level sinc
