* Britain's Kenny claims sixth career gold * Dutchman Matthijs Buchli clinches silver * Malaysia's Azizulhasni Awang takes bronze (Adds detail on controversy of restarts, quotes) By Stephen Eisenhammer RIO DE JANEIRO, Aug 16 (Reuters) - Britain's Jason Kenny won the men's track cycling keirin on Tuesday, taking his gold medal haul to six and equalling Chris Hoy's record for the country's most Olympic titles. In a race that was controversially restarted twice without disqualifying any riders, Kenny ultimately had too much pace down the final stretch, recovering from a slow start to finish just clear. After taking gold, Kenny embraced his fiancee and fellow gold medal winner Laura Trott, who was in tears in the centre of the track. More...