xfs_scrub: ignore freed inodes when single-stepping during phase 3

xfs_scrub: ignore freed inodes when single-stepping during phase 3

For inodes that inumbers told us were allocated but weren't loaded by
the bulkstat call, we fall back to loading bulkstat data one inode at a
time to try to find the inodes that are too corrupt to load.

However, there are a couple of outcomes of the single bulkstat call that
clearly indicate that the inode is free, not corrupt.  In this case, the
phase 3 inode scan will try to scrub the inode, only to be told ENOENT
because it doesn't exist.

As an optimization here, don't increment ocount, just move on to the
next inode in the mask.

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