[XFS] implement generic xfs_btree_updkey

[XFS] implement generic xfs_btree_updkey

From: Dave Chinner <[email protected]>

Note that there are many > 80 char lines introduced due to the
xfs_btree_key casts. But the places where this happens is throw-away code
once the whole btree code gets merged into a common implementation.

The same is true for the temporary xfs_alloc_log_keys define to the new
name. All old users will be gone after a few patches.

[hch: split out from bigger patch and minor adaptions]

SGI-PV: 985583

SGI-Modid: xfs-linux-melb:xfs-kern:32193a

Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Lachlan McIlroy <[email protected]>
Signed-off-by: Bill O'Donnell <[email protected]>
Signed-off-by: David Chinner <[email protected]>