avoid leaking stat info

avoid leaking stat info

if a file is already CStatd we just copy out the information without doing
access checks. add an access check.

Reviewed-on: http://gerrit.openafs.org/995
Tested-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit 6ec18461649d3e4f44b2476f886bcc480c456500)

Change-Id: I4a66c9e4229da464592c1dad94854261e5daa30d
Reviewed-on: http://gerrit.openafs.org/1076
Tested-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Derrick Brashear <shadow@dementia.org>