Use correct syntax for libtool version info

It does not take an '='.

Whomever thought that making libtool silently accept all (i.e.,
malformed) command-line arguments was a good idea ... seems to
have been mistaken.

Change-Id: I357cd44ac6f495474f9763a2f768ac9c8d1e4cb4
Reviewed-on: http://gerrit.openafs.org/11458
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Reviewed-by: D Brashear <shadow@your-file-system.com>
Tested-by: D Brashear <shadow@your-file-system.com>