AND WAIT, THERE'S MORE:Veteran songwriter Jimmy Webb is doing the score for "Hanoi Hilton," the upcoming Cannon film about a group of American POWs held captive in North Vietnam. Webb was in London last week, recording material with a 60-piece symphony orchestra. . . . Forget what we said last week. The upcoming film, "Adventures in Baby Sitting," has a new version of "Babysitting Blues," this one written and produced by Robert Craft, who produced the current Bruce Willis album. It's performed by blues guitarist Albert Collins and Elizabeth Shue, who stars in the Disney picture.