So what’s the buzz on Sundance at the halfway point? Ho-hum. “This is not to say that the 21st incarnation of Robert Redford’s independent baby hasn’t had its moments — the biggest thus far being Craig Brewer’s gritty urban drama “Hustle & Flow” — but the first half of the festival has been marked more by tame audience reactions and subdued wheeling and dealing than buzz, with films drawing more shrugs than love.”