generic: add test for fsync after renaming and linking special file

generic: add test for fsync after renaming and linking special file

Test that when a fsync journal/log exists, if we rename a special file
(fifo, symbolic link or device), create a hard link for it with its old
name and then commit the journal/log, if a power loss happens the
filesystem will not fail to replay the journal/log when it is mounted
the next time.

This test is motivated by a bug found in btrfs, which is fixed by the
following patch for the linux kernel:

  "Btrfs: fix log replay failure after linking special file and fsync"

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>