Wednesday was a day at Cannes for a wunderkind and an icon. The former was 25-year-old Xavier Dolan, precocious enough to already have made five movies and gone to Cannes with four of them. The latter was 83-year-old Jean-Luc Godard, who has made more than 50 features and brought many of them to Cannes, though his idea of “bringing” a film to Cannes does not always involve him attending the …