Arby’s is buying Buffalo Wild Wings, the chain of sports bars, for $2.9 billion.                    In an all-cash deal, Arby’s is paying $157 per share for Buffalo Wild Wings, a 7 percent premium based on Monday’s closing price. Buffalo Wild Wings stock had been much lower before rumors about a deal with Arby’s surfaced two weeks ago.                    The stock rose again in premarket trading Tuesday on news of the purchase agreement.                                                                                                                                                   The deal will take Buffalo Wild Wings private. Arby’s is owned by Roark Capital, which also has big stakes in Auntie Anne’s, Carvel and Jimmy John’s.                                   Analysts have also speculated that the chain could be hurt by lower NFL ratings this season, and some of the controversy swirling around the league. But company officials, while reporting better than expected earnings recently, said they had not seen evidence of a hit from the NFL’s problems.