“Fighting out of the red corner,’’ the announcer bellowed into the microphone, “from the fighting city of Lowell, Massachusetts - Please welcome, Sean Eklund.’’ The 1,200-plus locals in the crowd roared in a way that they have not for close to two decades. It was a homecoming, in so many ways. The 28-year-old Eklund and his childhood friend “Irish’’ Joey McCreedy were fighting in their own homecoming in separate bouts Wednesday night at the Lowell Memorial Auditorium, there as boxing professionals for the first time since they strapped on gloves as amateurs in their city’s annual Golden Gloves tournament. And in their corner were Eklund’s uncles, “Irish’’ Micky Ward and his older brother Dicky Eklund, the hometown boxing heroes whose triumphs and troubles of a dysfunctional family were chronicled in the blockbuster movie, “The Fighter.’’