ihandle: don't keep reallyclosing future fds

given that we can mark something invalid for future use, ever,
once we have done so for all fds, we ih_reallyclose is done.
don't persist the setting to the detriment of new fds

Reviewed-on: http://gerrit.openafs.org/6101
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Alistair Ferguson <alistair.ferguson@mac.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>
(cherry picked from commit 2332ee3aa8e21738ed4aa42b53edd4e2ae0a2984)

Change-Id: Ic77354893101acda867aa8e4c8ea7a2932666d5b
Reviewed-on: http://gerrit.openafs.org/9490
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>
Tested-by: BuildBot <buildbot@rampaginggeek.com>