auth: Relocate NetRestrict support functions

auth: Relocate NetRestrict support functions

Pull the NetRestrict and NetInfo support functions out of libutil,
and into libauth. This starts to concentrate all of our configuration
file parsing functions into the same place.

It also gets rid of a circular dependency. NetRestrict parsing relies
on functions from rx, so with this in libutil, we had the dependency
chain util->rx->util

Change-Id: I250d4d8264da8db61f603a06d1b7fdab44384cd3
Reviewed-on: http://gerrit.openafs.org/8027
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>