Build libafscp when we lack kerberos

Build libafscp when we lack kerberos

Currently, venus fails to build without kerberos, since the
dependencies for afsio always include afscp.h, which does not exist
when we do not build libafscp. To fix this the easy way, and since
libafscp is still very useful without kerberos, allow libafscp to
build without kerberos support (which limits it to anonymous
connections only).

Reviewed-on: http://gerrit.openafs.org/4577
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
(cherry picked from commit 64c92b24447aa1a86a4557d6bab3a72b38640fce)

Change-Id: I32ad1e26ab4f45647a69c0641e3027006e28bc2e
Reviewed-on: http://gerrit.openafs.org/5385
Reviewed-by: Derrick Brashear <shadow@dementix.org>
Tested-by: Derrick Brashear <shadow@dementix.org>