GLOBAL MARKETS-Euro hits 9-year low as Brent oil goes below $50

* Euro hits 9-year low* Brent oil breaks below $50* Nervousness ahead of euro zone inflationBy Jamie McGeeverLONDON, Jan 7 (Reuters) - The euro hit a nine-year trough on Wednesday as collapsing oil prices and worries about the world economy drove skittish investors into the arms of safe-haven sovereign debt.From Japan to Germany to Australia, government borrowing costs fell to all-time lows as oil