e2fsck: add support for dirdata feature

e2fsck: add support for dirdata feature

Add support for the INCOMPAT_DIRDATA feature, which allows
storing extra data in the directory entry beyond the name.
This allows the Lustre File IDentifier to be accessed in
an efficient manner, and would be useful for expanding a
filesystem to allow more than 2^32 inodes in the future.

While adding the new file entry in directory block, link_proc()
calculates minimum record length of the existing directory entry
without considering the dirent data size and which leads to
corruption. Changed the code to use EXT2_DIR_REC_LEN() which will
return correct record length including dirent data size.

Change-Id: I1b81948b5bf114822ab140cb989c3a7e81fdc6f5
Lustre-bug-id: https://jira.hpdd.intel.com/browse/LU-4677
Signed-off-by: Pravin Shelar <pravin@clusterfs.com>
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Signed-off-by: Artem Blagodarenko <artem.blagodarenko@gmail.com>