(Reuters) - Facebook Inc's efforts to establish a global digital currency called Libra suffered major setbacks on Friday, as EBay Inc , Stripe Inc, Mastercard and Visa Inc all said they were leaving a group of companies aiding the project.The companies join PayPal Holdings Inc which exited the Libra Association just a week ago, as global regulators continue to air concerns about the project."Visa has decided not to join the Libra Association at this time," the company said in a statement...