[XFS] Add versioning to the on disk inode which we increment on each

[XFS] Add versioning to the on disk inode which we increment on each
flush call. This is used during recovery to avoid replaying an
older copy of the inode from the log. We can do this without
versioning the filesystem as the pad space we borrowed was
always zero and will be ignored by old kernels.

SGI Modid: 2.5.x-xfs:slinx:155189a