KHARTOUM, May 11 (Reuters) - Sudanese president Omar Hassan al-Bashir underwent successful mi**r surgery on one of his knees on Sunday and will handle his duties from a Khartoum hospital for two to three days as he recovers, a presidential spokesman said. Bashir, 70, also had a mi**r operation on his vocal cords in Qatar in 2012. The Islamist leader is facing an armed rebellion in the western region of Darfur and dealing with an eco**mic crisis which prompted violent protests last year. He has been indicted by the International Criminal Court on charges of masterminding war crimes in Darfur. ...