git-version: Do not specify --ignore-submodules

git-version: Do not specify --ignore-submodules

Only new git versions reognize the --ignore-submodules option to
diff-index and diff-files. Do not pass this, to make git-version more
likely to work across different versions, as we don't have any
submodules in the tree anyway.

Reviewed-on: http://gerrit.openafs.org/3627
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit 60322b46755d0bfedc239e3e9287f6ae625cd836)

Change-Id: Iae527081b431863fa1eae418b8468741f75f3f2e
Reviewed-on: http://gerrit.openafs.org/3817
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>