ubik: Remove dependency on auth

ubik: Remove dependency on auth

When commit 8a09c220f4c5f881ea45be585b07b793038924d5 added support
for token error recovery to ubik, it introduced a dependency on
afsconf. This breaks the abstraction layer that had been in place, by
requiring that the SecurityRock be an afsconf_dir (if you use a
different rock, ubik will segfault)

This change reinstates the abstraction layer, by requiring Ubik
users who want token error checking to specify a procedure that can
be used to check whether tokens are up to date. Instead of yet
another global variable, we replace the existing CRXSecurity*
variables with a single function that can be used to set security proc,
token checking proc, and rock.

Change-Id: I9036cf712f02610ed2e906602d3416436f69e98b
Reviewed-on: http://gerrit.openafs.org/4200
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>