BENGHAZI, Libya, Sept 12 (Reuters) - An American staff member of the U.S. consulate in the eastern Libyan city of Benghazi has died following fierce clashes at the compound, Libyan security sources said on Wednesday. "One American staff member has died and a number have been injured in the clashes," Abdel-Monem Al-Hurr, spokesman for Libya's Supreme Security Committee, said, adding that he did not know the exact number of injured and could not say what the cause of death was. Armed gunmen attacked the compound on Tuesday evening, clashing with Libyan security forces before the latter withdrew as they came...