Adding dirhash hint to filesystem.

Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information

test_filesys: ***** FILE SYSTEM WAS MODIFIED *****
test_filesys: 12/2048 files (0.0% non-contiguous), 1294/2048 blocks
Exit status is 0