(Adds quote, background) DUBAI, Dec 10 (Reuters) - A Twitter account associated with Iranian Supreme leader Ayatollah Ali Khamanei said on Wednesday that a U.S. Senate report into CIA torture showed the U.S. government was a "symbol of tyranny against humanity". In a message bearing the hashtag "TortureReport", used to connect comments on the topic on the social media platform, the account said: "Today, U.S. govt. is symbol of tyranny against humanity". ...