xfs_repair: require zeroed quota/rt inodes in metadir superblocks

xfs_repair: require zeroed quota/rt inodes in metadir superblocks

If metadata directory trees are enabled, the superblock inode pointers
to quota and rt free space metadata must all be zero.  The only inode
pointers in the superblock are sb_rootino and sb_metadirino.

Found by running xfs/418.

Fixes: b790ab2a303d58 ("xfs_repair: support quota inodes in the metadata directory")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>