libafscp: add lock support

libafscp: add lock support

add support for locking as well as for tracking callbacks so a
lock break can be detected

Reviewed-on: http://gerrit.openafs.org/4476
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit f4ae9ef6531cb629e0bac2233d97cf8a0f3a698b)

Change-Id: I2011486d6d604dbebf9f91afd7eebd50b5438e16
Reviewed-on: http://gerrit.openafs.org/5384
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>