Stale symlinks in vfs

[andrew_b]

How to reproduce:

1. Create any temporary dir
2. cd to this temporary dir

3. Create two archives:

     mkdir -p a/b
     touch a/b/d
     ln -s d a/b/e
     tar -cf good.tar a
     rm -rf a
     mkdir -p a/b/c
     touch a/b/c/d
     ln -s d a/b/c/e
     tar -cf bad.tar a
     rm -rf a
   

4. Enter to the good.tar and cd to a/b. Symlink e points to d and it is not stale.
5. Enter to the bad.tar and cd to a/b/c. Symlink e points to d and it is stale.

The difference between that symlinks is a deep where symlink is. The deep of 2 or less directories is ok, symlinks are not stale. The deep of 3 or more directories is not ok, symlinks are stale.

Bisect told that first bad commit is [e2c326997f703ca111a7d3e079c12c26aeaddcbe].

[slavazanko]

created branch 2777_vfs_stale_symlinks

Review, please.

[slavazanko]

Merged to master:

git log --pretty=oneline 876e006..33ea909

[slavazanko]

Also merged to stable