ext4: test mounting filesystem with encrypted inode on orphan list

ext4: test mounting filesystem with encrypted inode on orphan list

Add an ext4-specific regression test for a bug which caused ext4 to
crash when mounting a filesystem which had an encrypted inode on its
orphan list.

This bug was present in kernels v4.1 and later.  It has been fixed
in v4.11-rc1, v4.10.4, v4.9.16, and v4.4.55.

Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Michael Halcrow <mhalcrow@google.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>