CHAPEL HILL — It’s becoming something of a sporting cliché in recent times: the player’s-only meeting. We hear about these in all sports, and they seem to come around whenever a team encounters a rough patch. North Carolina has suffered through some difficult times, indeed, so far. The Tar Heels lost for the fourth time when they came apart during the second half of their 61-52 defeat at Virginia on Sunday. On Monday, Roy Williams gathered his players for film study and meetings, and Williams during his radio show earlier this week said the Heels spent more than three hours together.