Warren Buffett has said for years that airlines were a lousy investment. Until he decided they weren’t. Buffett’s Berkshire Hathaway disclosed big investments in the major airlines yesterday — 21.8 million shares of American, 6.3 million of Delta and 4.5 million of United. He said he also bought some Southwest stock for good measure. Warren Buffett is a billionaire who invests for the long term. What does his new high hopes for airlines mean for their customers?