If summer started off white-hot with Marvel’s The Avengers, it looks like it will end ice-cold with the lowest-grossing number one finish of 2012.  After a weak Friday box office, it looks like The Expendables 2 will earn a second weekend at number one with just $11 million in expected grosses. The weekend’s other titles should all fall short of $10 million by Sunday, including the new releases Premium Rush, Hit and Run and The Apparition. The only notable feature of Friday’s top five is the performance of the political documentary 2016 Obama’s America. After hanging back in limited release since July, the feature-length attack ad moved into 1,091 locations on Friday where it brought in a solid $2.2 million. We’ll have full details tomorrow.