selftests/sched_ext: testing on BPF CI

[Ihor Solodrai]

Hi Tejun, Andrea.

I tested a couple of variants of bpf-next + sched_ext source tree,
just sharing the results.

I found a working state: BPF CI pipeline ran successfully twice
(that's 8 build + run of selftests/sched_ext/runner in total).

Working state requires most patches between sched_ext/master and
sched_ext/for-6.14-fixes [1], and also the patch
  "tools/sched_ext: Receive updates from SCX repo" [2]

On plain bpf-next the dsp_local_on test fails [3].
Without the patch [2] there is a build error [4]: missing
SCX_ENUM_INIT definition.

We probably don't want to enable selftests/sched_ext on BPF CI with
that many "temporary" patches. I suggest to wait until all of this is
merged upstream.

You can check the full list of patches here:
https://github.com/kernel-patches/vmtest/pull/332/files

[1] https://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git/log/?h=for-6.14-fixes
[2] https://lore.kernel.org/all/Z1ucTqJP8IeIXZql@xxxxxxxxxxxxxxx/
[3] https://github.com/kernel-patches/vmtest/actions/runs/13019837022
[4] https://github.com/kernel-patches/vmtest/actions/runs/13020458479