ubik: Allow servers to have more than 3 seclayers

ubik: Allow servers to have more than 3 seclayers

ubik has traditionally used the afsconf_ServerAuth function to
fill in a single field in a pre-allocated list of security classes.
This meant that we could never have a class with an index higher
than 2 (rxkad). Setting the function to call, and the rock to that
function was also accomplished by playing with global variables.

Rework this so that a new function is used to set the security
classes, which can allocate an arbitrary sized array of classes.
Move the setting of this function, and of the authentication check
function into ubik_SetServerSecurityProcs()

Change-Id: I7cde73b05db4d51403469e2bead1d99d5ae88043
Reviewed-on: http://gerrit.openafs.org/4202
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>