db/check: handle zero inoalignmt correctly for large block sizes

db/check: handle zero inoalignmt correctly for large block sizes

The check command prints a spurious error when sb_inoalignmt is zero but
the sb align feature bit is set:

$ mkfs.xfs -f -bsize=16k <dev>
$ xfs_db -c "check" <dev>
sb versionnum extra align bit 80

This occurs because check determines whether to expect the alignment
feature bit based on a non-zero inoalignmt (in init()). sb_inoalignmt of
0 is expected for block sizes that are large enough for at least one
full inode record (64 inodes), however. For example, when bsize >= 16k
on v4 filesystems or >=32k on v5 filesystems.

Update the init() logic in the check command to detect this particular
scenario. Set the in-memory feature bit if inoalignmt is zero and the
block size is large enough for full inode records such that blockget_f()
does not complain.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>