‘Love is an action. It’s not something you get. It’s something you do, and it manifests into something greater than you are. Which is perfect.’ Robyn Coburn, the 1999 Academy Award victor’s daughter-in-law, untethers a wealth of absorbing nuggets from ‘Dervish Dust.’ — Affectionately tagged “the philosopher” by martial arts master Bruce Lee, James Coburn shot to fame as ladykiller spy Derek Flint in two tongue-in-cheek action movies in the swinging ’60s and counted Steve McQueen, Charles Bronson, and Sam Peckinpah as mates. Equally at home on the range — The Magnificent Seven…