fix init script install rules for linux and darwin

fix init script install rules for linux and darwin

the mode needs to be provided before src dest; do so, so we get boot scripts
again

Reviewed-on: http://gerrit.openafs.org/http://gerrit.openafs.org/156
Reviewed-by: Simon Wilkinson <sxw@inf.ed.ac.uk>
Tested-by: Russ Allbery <rra@stanford.edu>
Reviewed-by: Russ Allbery <rra@stanford.edu>