[PATCH 1/9 V2] Use xfs.h rather than libxfs.h

[Christoph Hellwig]

> +#ifndef XFS_SUPER_MAGIC
> +#define XFS_SUPER_MAGIC 0x58465342
> +#endif

This should eventually be replaced by just using platform_test_xfs_fd
from xfs.h


But for now the patch is fine,


Reviewed-by: Christoph Hellwig <hch at lst.de>