Comment 1 for bug 1869825

5.11.0-22-generic can no longer compile kvdo from source, failing with:

```
Skipping BTF generation for /src/kvdo/vdo/kvdo.ko due to unavailability of vmlinux
make: Leaving directory '/usr/src/linux-headers-5.11.0-22-generic'
```

Even though ddebs + dbgsym are installed. :(

An Ubuntu package / support for dm-vdo would be hugely impactful.