namei: Ignore misplaced files

The namei salvaging/ListViceInodes code currently ignores files where
we cannot derive an inode number from a given filename. However, if a
file is a valid inode filename, but is in the wrong directory, we
still record it. This can cause the salvager to abort, since it
assumes inode e.g. 12345 is present, but when it tries to open 12345,
namei translates the inode to a nonexistant path, and we bail out.

It is unknown how a namei directory structure can reach this state,
but try to handle it. To be on the safe side, just ignore the files,
and log a message about them. That way, if the files are required for
reconstructing the volume or contain important data, they are still
available if needed. And if they contain incorrect or old data, we
don't screw up the volume by trying to use them.

Thanks to Sabah S. Salih for reporting a related issue.

Reviewed-on: http://gerrit.openafs.org/10214
Reviewed-by: D Brashear <shadow@your-file-system.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
(cherry picked from commit 1096582bde6156bb469f2e397cbc40d13a8f2822)

Change-Id: I9252877fbfe01328ac4a8692ebe28a86913b9713
Reviewed-on: http://gerrit.openafs.org/10810
Reviewed-by: D 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>