generic: test directory fsync after rename operation

generic: test directory fsync after rename operation

Test that if we move one file between directories, fsync the parent
directory of the old directory, power fail and remount the filesystem,
the file is not lost and it's located at the destination directory.

This is motivated by a bug found in btrfs, which is fixed by the patch
(for the linux kernel) titled:

  "Btrfs: fix file loss on log replay after renaming a file and fsync"

Tested against ext3, ext4, xfs, f2fs and reiserfs.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>