xfs: add fsgeom flag for v5 superblock support.

xfs: add fsgeom flag for v5 superblock support.

Currently userspace has no way of determining that a filesystem is
CRC enabled. Add a flag to the XFS_IOC_FSGEOMETRY ioctl output to
indicate that the filesystem has v5 superblock support enabled.
This will allow xfs_info to correctly report the state of the
filesystem.

Signed-off-by: Dave Chinner <[email protected]>
Reviewed-by: Eric Sandeen <[email protected]>
Reviewed-by: Brian Foster <[email protected]>
Signed-off-by: Ben Myers <[email protected]>