NEW YORK—"We're not popular because we're not sensational," Supertramp's co-founder Roger Hodgson is explaining between pina coladas. "We're boring old farts." Very true that this, bunch of voluntarily self-exiled Britishers isn't exactly swamped with salivating fans on the street—yet. But they have caused riots in a tiny Vermont town, banning the rock there forever, and been given a key to the city of Fresno by its 28-year-old mayor. And with "Give A Little Bit" from their. latest LP, Even in the Quietest Moments, comfortably gliding through the Top Ten, it's merely a matter of, say, one more tour before the bearded fivesome learns all about adulation.