WASHINGTON (Reuters) -Vietnamese Foreign Minister Bui Thanh Son said on Tuesday the resignation of the communist-ruled country's third president in little over a year has not affected Hanoi's foreign and economic policies, given its collective leadership and policymaking. Asked during a visit to the United States about Vo Van Thuong's resignation last week, Son told Washington's Brookings Institution think tank Vietnam was undergoing an anti-corruption campaign that has been welcomed by the inte