Goo Goo Dolls frontman John Rzeznik has been known to vent a little angst in the band’s songs -- though frequently with hit-making results such as “Name,” “Iris,” “Slide” and “Black Balloon.”So it’s hard not to be disarmed, initially, by the upbeat tone of the Goos’ latest album, “Boxes.”“It’s not what I intended,” Rzeznik, 50, says with a laugh from his record company’s offices in Burbank, Calif. “That wasn’t my intention at the beginning of it. But as it went along it just sort of took shape that way. It’s got to be sort of a reflection of where you’re head’s at, and I’m definitely in a grea