Presidential candidate for the ruling Frente Amplio party Tabare Vazquez casts his vote in a polling station in MontevideoBy Malena Castaldi and Esteban Farat MONTEVIDEO (Reuters) – Tabare Vazquez won back his old job as president of Uruguay in a runoff election on Sunday, extending the decade-long rule of a leftist coalition and allowing it to roll out a groundbreaking law that legalizes the production and sale of marijuana. Vazquez won comfortably with 52.8 percent support while his center-right challenger, Luis Lacalle Pou, trailed on 40.5 percent, official results showed late on Sunday night. …