diriv: fix Symlink() and Readlink()
diriv: fix Symlink() and Readlink()

Both were missing adaptions for diriv usage resulting in broken
functionality

davesteele/gocryptfs,rfjakob/gocryptfs,davesteele/gocryptfs,rfjakob/gocryptfs,davesteele/gocryptfs,rfjakob/gocryptfs,rfjakob/gocryptfs