CONCORD, N.C. — Tens of thousands of fans are packing Charlotte Motor Speedway and the campgrounds for this weekend’s All-Star Race. It some ways it's one big party. In so many others, the friendships made between fellow campers last a lifetime. In the camping area behind turn three, a wife who lost her husband to cancer returned to the speedway this year for the first time since his death. The "C" in row C of the Hellman's Mayonnaise campground might as well stand for "Canadian," given all of the campers