xfs_io: add support for atomic write statx fields

xfs_io: add support for atomic write statx fields

Add support for the new atomic_write_unit_min, atomic_write_unit_max, and
atomic_write_segments_max fields in statx for xfs_io. In order to support builds
against old kernel headers, define our own internal statx structs. If the
system's struct statx does not have the required atomic write fields, override
the struct definitions with the internal definitions in statx.h.

Signed-off-by: Catherine Hoang <catherine.hoang@oracle.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: John Garry <john.g.garry@oracle.com>