getopt can be provided by either util-linux or busybox. Allow the
distro to control which implementation is used, and default it to
util-linux.
Signed-off-by: Richard Tollerton <rich.tollerton@ni.com> Acked-by: Ken Sharp <ken.sharp@ni.com> Acked-by: Ben Shelton <ben.shelton@ni.com Acked-by: Brad Mouring <brad.mouring@ni.com> Signed-off-by: Ross Burton <ross.burton@intel.com>