aklog: Fix some format warnings

aklog: Fix some format warnings

Fix some format warnings (size_t vs int) which only appear when we're
building with Heimdal.

Reviewed-on: http://gerrit.openafs.org/2740
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit 5bc4b4956509256e8cf13bd04e4615ee2cb31c65)

Change-Id: Ifac99313d96dcd3d33733ffd75db752ab3854608
Reviewed-on: http://gerrit.openafs.org/3986
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>