xfs_db: fix metadump name obfuscation for ascii-ci filesystems

xfs_db: fix metadump name obfuscation for ascii-ci filesystems

Now that we've stabilized the dirent hash function for ascii-ci
filesystems, adapt the metadump name obfuscation code to detect when
it's obfuscating a directory entry name on an ascii-ci filesystem and
spit out names that actually have the same hash.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>