When Wayne Wang was scrambling around the streets of Chinatown in the early 1980s shooting his indie feature “Chan Is Missing,” trying to stretch the most out of the $22,000 he’d scrounged together to make it, even he couldn’t guess that he was making a landmark movie. He figured his noirish 16mm black-and-white film about two cabdrivers searching for a guy who owes them money would play at festivals, college campuses and Chinese American communities.