“Idol Gives Back,” the charity fund-raiser sponsored by “American Idol” and its producers, will return next season for a third installment of raising money for impoverished children around the world. The charity event will take place on April 21 during the “American Idol” results show featuring the top seven contestants from the annual talent competition. “American Idol” is scheduled to begin broadcasting its ninth season in January. In 2008, the second installment of the “Idol Gives Back” event