BAGHDAD (Reuters) - Iraqi Prime Minister Adel Abdul Mahdi sought on Monday to curb the powers of influential Iranian-backed Shi’ite Muslim militias, a politically risky move apparently aimed at placating the United States. Iraq's Prime Minister Adel Abdul Mahdi attends the opening of Baghdad International Fair in Baghdad, Iraq, November 10, 2018. REUTERS/Thaier al-SudaniTwo weeks…