EMERGING MARKETS-Brazil stocks slip on profit-taking

* Brazil's Bovespa snaps 3-day rally * OGX gains after starting oil production at well * Brazil Bovespa falls 0.95 pct, Mexico IPC flat By Asher Levine and Danielle Assalve SAO PAULO, Jan 4 (Reuters) - Brazilian stocks fell on Friday as investors sold off shares of commodities producers following a three-day rally that saw the index rise nearly 5 percent. Mexico's IPC index remained mostly flat, while Chile's bourse extended its rally into a fourth day. Brazil's benchma