afsconf: Rework security flags

afsconf: Rework security flags

BuildServerSecurityObjects takes a set of flags, which makes it
hard to use it as a callback function. Rework this so that the
security flags are part of the afsconf directory structure, and
so BuildServerSecurityObjects only takes a rock, and its return
parameters.

Update all of the callers for this new function, and add tests
for it to the test suite.

Change-Id: I48219ed199d128c6aec3765ca425bda9e464b937
Reviewed-on: http://gerrit.openafs.org/4201
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>