U.S. stock index futures were little changed on Friday, though recent weakness was enough to put the Dow and S&P 500 on track for their first weekly decline after three consecutive weeks of gains. * While both the Dow and S&P hit a series of record highs this week, Wall Street has lately been pressured by concerns of slowing global growth and ongoing violence in Iraq, which has taken oil prices to their highest since September. * The S&P has fallen for three straight days, its longest streak of declines since early April.