Australia shares seen subdued as Wall Street falters

SYDNEY, Oct 21 (Reuters) - Australian shares are set for a lacklustre start on Wednesday with a negative finish on Wall Street and a mixed performance in commodity prices likely to weigh on investors already fretting about slower Chinese growth. Stock index futures eased 0.3 percent to 5,199.0, a 36.6-point discount to the underlying S&P/ASX 200 index. The benchmark ended 0.7 percent lower on Tuesday. Ahead of the opening bell, BHP Billiton announced its operational review for the third