Boeing’s new chairman gave embattled CEO Dennis Muilenburg a vote of confidence Tuesday and said the chief executive is giving up any bonus this year. David Calhoun said the Boeing board believes Muilenburg “has done everything right” and is positioning the Chicago company to return the 737 Max to service after two accidents killed 346 people. A flight-control system called MCAS pushed the nose of both planes down before crashes in Indonesia and Ethiopia.