Push kernel lock from ifioctl() into ifioctl_get()

Push kernel lock from ifioctl() into ifioctl_get()

Recommit these two together:
- r1.667 "Push kernel lock into ifioctl_get()"
  locked before the switch() without unlocking in its cases
- r1.668 "Push kernel lock inside ifioctl_get()"
  locked cases individually, as intended

I messed up splitting commits, but of course, Hrvoje managed to test a
CVS checkout right inbetween those two.

OK mpi mvs