Build kopenafs with libtool

Prior to this commit, we were installing libkopenafs.so.1.1.  As
for the other libtoolizations, bump SONAME to 2.0 as a general
precaution.

Change-Id: I6edef89737cf057eb8aab8dfe2eacfb4f417dd6e
Reviewed-on: http://gerrit.openafs.org/11484
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: D Brashear <shadow@your-file-system.com>