Comment 0 for bug 1722800

Being on Ubuntu 16.04 I've first installed libguestfs-tool and then libguestfs-zfs.
The latter is supposed to bring ZFS filesystem support, but it doesn't. Here is how
I've tested:

```
$ sudo guestfish -N fs:zfs:2GB
libguestfs: error: mkfs: zfs: /dev/sda1: mkfs: failed to execute mkfs.zfs: No such file or directory
guestfish: error creating prepared disk image 'fs:zfs:2GB' on 'test1.img': failed to create filesystem (zfs): mkfs: zfs: /dev/sda1: mkfs: failed to execute mkfs.zfs: No such file or directory
```

I don't think there is much I could do wrong in the process, I'm quite confident it's a bug in the libguestfs-zfs package. I kindly ask for a fix or patch.

PS: Here is the list of packages that I have installed:
```
$ apt list --installed | grep guestfs

libguestfs-dev/xenial,now 1:1.32.2-4ubuntu2 amd64 [installed]
libguestfs-gfs2/xenial,now 1:1.32.2-4ubuntu2 amd64 [installed]
libguestfs-hfsplus/xenial,now 1:1.32.2-4ubuntu2 amd64 [installed,automatic]
libguestfs-perl/xenial,now 1:1.32.2-4ubuntu2 amd64 [installed,automatic]
libguestfs-reiserfs/xenial,now 1:1.32.2-4ubuntu2 amd64 [installed,automatic]
libguestfs-rescue/xenial,now 1:1.32.2-4ubuntu2 amd64 [installed]
libguestfs-rsync/xenial,now 1:1.32.2-4ubuntu2 amd64 [installed]
libguestfs-tools/xenial,now 1:1.32.2-4ubuntu2 amd64 [installed]
libguestfs-xfs/xenial,now 1:1.32.2-4ubuntu2 amd64 [installed]
libguestfs-zfs/xenial,now 1:1.32.2-4ubuntu2 amd64 [installed]
libguestfs0/xenial,now 1:1.32.2-4ubuntu2 amd64 [installed]
lua-guestfs/xenial,now 1:1.32.2-4ubuntu2 amd64 [installed]
```