If Josh Brolin, playing a villain, resembles Donald Trump in “Wall Street 2,” it could be because he studied the tycoon up close the other night at ’21’ over dinner with director Oliver Stone and co-star Shia LaBeouf. Brolin was almost uncanny in his depiction of the 43rd president in “W.,” and he probably would have no trouble impersonating the supremely confident Trump in Stone’s film after picking his brain for entrepreneurial knowledge — even though Trump has mainly avoided the paper profits of Wall Street and made his money with bricks and mortar.