EMERGING MARKETS-Latam stocks down on Syria uncertainty

* Possible U.S. military action drives shares down, dollar up * Oil watchdog rejects OGX plan to modify production site * Brazil Bovespa down 1.55 pct, Mexico IPC falls 0.73 pct By Lucas Iberico-Lozada SAO PAULO, Aug 27 (Reuters) - Brazilian stocks tracked world markets lower on Tuesday, as uncertainty over potential U.S. military action against the Syrian government drove investors away from risky assets. Mexico's IPC index declined for the fifth session in a row, while Chi