Make OpenAFS 1.8.6pre2

Make OpenAFS 1.8.6pre2

Update version strings for the second 1.8.6 prerelease.

Change-Id: Ic5e452a379dac906520040a451f84ca19fd158e1
Reviewed-on: https://gerrit.openafs.org/14097
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Reviewed-by: Yadavendra Yadav <yadayada@in.ibm.com>
Reviewed-by: Cheyenne Wills <cwills@sinenomine.net>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>