xfs: add an x86 compat handler for XFS_IOC_ZERO_RANGE

XFS_IOC_ZERO_RANGE uses struct xfs_flock64, and thus requires argument
translation for 32-bit binaries on x86.  Add the required
XFS_IOC_ZERO_RANGE_32 defined and add it to the list of commands that
require xfs_flock64 translation.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>