tests: Add new test f_unused_itable

Add test to make sure e2fsck doesn't end up detaching and sending to
lost+found inodes which are in an bg_itable_unused_region (e.g. if
there was a power failure and bg_itable_unused wasn't updated because
journaling wasn't enabled).

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
4 files changed