xfs/{080,329,434,436}: add missing check for fallocate support

xfs/{080,329,434,436}: add missing check for fallocate support

Don't run this test if the filesystem doesn't support fallocate.  This
is only ever the case if always_cow is enabled.

The same logic applies to xfs/329, though it's more subtle because the
test itself does not explicitly invoke fallocate; rather, it is xfs_fsr
that requires fallocate.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Zorro Lang <zlang@kernel.org>