Comment 16 for bug 1872183

As expected I was able to reproduce locally in autopkgtest.

The bionic kernel headers didn't change actually (which is good!).
The test creepign into Bionic fail is actually the inverse:
1. gettimeofday changed upstream
2. upstream clknetsim adapted
3. since Eoan we download defined versions matching the release
4. the bionic test still was the "uncontrolled" cloning of latest master
   which now no more matches bionic kernel headers

Focal uses clknetsim_ver=79ffe44, but that is for the new kernel behavior.
Eoan used clknetsim_ver=156b8e4 which works well in Bionic.

Furthermore between Eoan and Focal the test has gotten a bigger rewrite and some fixes.

In the SRU-spirit lets keep the changes minimal by:
- picking the version from Eoan
- add just one small fixups
  (ignoring stderr on make since gcc warnings trigger false positives).

That should do it, I'll be back here once I have some proven bionic test results.