t_snapshot_deleted_subvolume: add check for BTRFS_IOC_SNAP_DESTROY_V2

t_snapshot_deleted_subvolume: add check for BTRFS_IOC_SNAP_DESTROY_V2

On some platform, struct btrfs_ioctl_vol_args_v2 is defined, but the
macros BTRFS_IOC_SNAP_DESTROY_V2 is not defined. This will cause
compile error. Add check for BTRFS_IOC_SNAP_DESTROY_V2 to solve this
problem.

BTRFS_IOC_SNAP_CREATE_V2 and BTRFS_IOC_SUBVOL_CREATE_V2 were
introduced together with struct btrfs_ioctl_vol_args_v2 by the
commit 55e301fd57a6 ("Btrfs: move fs/btrfs/ioctl.h to
include/uapi/linux/btrfs.h"). So there is no need to check them.

Signed-off-by: Yang Xu <xuyang2018.jy@fujitsu.com>
Reviewed-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Zorro Lang <zlang@kernel.org>