e2fsck: ignore badblocks if it says badblocks inode is bad

e2fsck: ignore badblocks if it says badblocks inode is bad

If the badblocks list says that the badblocks inode is bad, it's quite
likely that badblocks is broken.  Worse yet, if the root inode is in
the same block as the badblocks inode (likely since they're adjacent),
the filesystem becomes unfixable because pass3 notices the bad root
inode and exits.

So... if we encounter this case, just kill the badblocks inode.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>