Use an anonymous pointer for lpioctl

Use an anonymous pointer for lpioctl

The block passed to lpioctl as cmarg is an anonymous chunk of
memory, so use a type that represents it as such.

Reviewed-on: http://gerrit.openafs.org/238
Tested-by: Marc Dionne <marc.c.dionne@gmail.com>
Tested-by: Derrick Brashear <shadow@dementia.org>
Reviewed-by: Derrick Brashear <shadow@dementia.org>