xfs: add secondary and indirect classes to the health tracking system

Establish two more classes of health tracking bits:

 * Indirect problems, which suggest problems in other health domains
   that we weren't able to preserve.

 * Secondary problems, which track state that's related to primary
   evidence of health problems; and

The first class we'll use in an upcoming patch to record in the AG
health status the fact that we ran out of memory and had to inactivate
an inode with defective metadata.  The second class we use to indicate
that repair knows that an inode is bad and we need to fix it later.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>