Glossing over Vivienne Westwood’s association with the Sex Pistols is like barely mentioning the Civil War in a profile of Abraham Lincoln. But that’s exactly what Lorna Tucker does in her slipshod look at the celebrated fashion designer in “Westwood: Punk, Icon, Activist.” Come on, Viv’s interaction with Sid Vicious and Johnny Rotten is what everyone is slavering to get up close and personal about.