nlink restriction on files

[James Rhodes]

It would be nice if by default, AppArmor prevented file access being allowed to a file with nlink > 1 to close the hardlink problem (where you have two files with the same data, and applications can affect each other with the shared file). Optionally the rule could specify "nlink" as a prefix (like "audit" or "deny") that indicates that it should be permitted even if nlink > 1.