busybox: build without dc

dc is already provided by 9base and much more complete.
additionally 9base's bc is just a frontend to the dc program,
but uses features not provided by bb' dc (busybox lacks a bc
implementation).
so if you rebuilt busybox after 9base, and didnt recreate the
9base symlinks via butch relink, bc was using the wrong dc and
failed with error messages.
eudev: add patch that makes GROUP= work