vol_split: avoid using stale open directory vnodes

vol_split: avoid using stale open directory vnodes

we could in case of multiple splits end up using a stale open
vnode for a directory; attempt to close and thus force-reopen
any fdhandles backing ihandles.

Reviewed-on: http://gerrit.openafs.org/5553
Reviewed-by: Hartmut Reuter <reuter@rzg.mpg.de>
Tested-by: Derrick Brashear <shadow@dementix.org>
Reviewed-by: Derrick Brashear <shadow@dementix.org>
(cherry picked from commit 3df03f0abe3e706eaba57e4d9d8c46f2f4d7414c)

Change-Id: I4894b21ac3ee114f57192261220c002a2e213ae9
Reviewed-on: http://gerrit.openafs.org/5698
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>