ubuntu_bpf build failure on Hirsute - missing rst2man

[Krzysztof Kozlowski]

On Hirsute v5.11 the ubuntu_bpf fails to build with:

  make[1]: Leaving directory '/home/azure/autotest/client/tmp/ubuntu_bpf/src/linux/tools/testing/selftests/bpf'
  make: Leaving directory '/home/azure/autotest/client/tmp/ubuntu_bpf/src/linux/tools/testing/selftests'
  stderr:
  Warning: Kernel ABI header at 'tools/include/uapi/linux/netlink.h' differs from latest version at 'include/uapi/linux/netlink.h'
  Warning: Kernel ABI header at 'tools/include/uapi/linux/if_link.h' differs from latest version at 'include/uapi/linux/if_link.h'
  Makefile:45: *** "rst2man not found, but required to generate man pages". Stop.
  make[1]: *** [Makefile:188: /home/azure/autotest/client/tmp/ubuntu_bpf/src/linux/tools/testing/selftests/bpf/tools/sbin/bpftool] Error 2
  make[1]: *** Deleting file '/home/azure/autotest/client/tmp/ubuntu_bpf/src/linux/tools/testing/selftests/bpf/tools/sbin/bpftool'
  make: *** [Makefile:165: all] Error 2

[Krzysztof Kozlowski (krzk)]

Fix proposal

[Po-Hsu Lin (cypressyew)]

Found on 5.11.0-1013.14 linux-gcp

[Po-Hsu Lin (cypressyew)]

The package name should be docutils-common

We have a fix for focal already, by installing python-docutils. But on Hirsute you will need python3-docutils.

This can be simplified to just install the docutils-common, as these two packages all depend on it.

[Po-Hsu Lin (cypressyew)]

https://lists.ubuntu.com/archives/kernel-team/2021-July/122422.html