BP Plc cemented its 77-year relationship with Abu Dhabi by swapping about $2.2 billion of its own shares for a stake in one of the emirate’s largest onshore oil concessions.  The U.K.’s second-biggest oil group will issue new ordinary shares to pay for 10 percent of the Abu Dhabi Company for Onshore Petroleum Operations Ltd., giving the emirate a 2 percent holding in BP, the London-based company said Saturday in a statement. Abu Dhabi investor Mubadala Development Co.