Bold ugly fix so I can use reiser4 on 3.11 kernel now -> Revert "[readdir] ->readdir() is gone"

This reverts commit 2233f31aade393641f0eaed43a71110e629bb900.
Revert "[readdir] constify ->actor"

This reverts commit ac6614b76478e68173ccf7ad4e9e98035cc9c21d.
Switched back to readdir as it's back in the kernel