(Reuters) - Activist investor Appaloosa LP said on Monday that Allergan Plc's board was doing "everything except what needs to be done" in a series of concessions the drug company announced last week in response to criticism from the hedge fund. Allergan agreed to split its chairman and chief executive roles, but only at its next leadership change. A source close to Allergan told Reuters on Friday that current Chairman and CEO Brent Saunders, 49, has no plans to step down.