[PATCH 1/3] xfstests: add helper for zero range support check

[Christoph Hellwig]

> +# check that xfs_io, kernel, and filesystem all support fallocate with zero
> +# range
> +_require_xfs_io_falloc_zero()
> +{
> +	_require_xfs_io_command "fzero"
> +}

I'd rather remove all the wrappers around _require_xfs_io_command, they
don't actually add any value.