These fixes have been triggered by [0]:
basically, if you do not recompile the kernel first, and are
running on an old kernel, vmlinux.h doesn't have the required
symbols and the compilation fails.

The tests will fail if you run them on that very same machine,
of course, but the binary should compile.

And while I was sorting out why it was failing, I realized I
could do a couple of improvements on the Makefile.

[0] https://lore.kernel.org/linux-input/56ba8125-2c6f-a9c9-d498-0ca1c153dcb2@redhat.com/T/#t (local)

Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
---
Benjamin Tissoires (3):
      selftests/hid: ensure we can compile the tests on kernels pre-6.3
      selftests/hid: do not manually call headers_install
      selftests/hid: force using our compiled libbpf headers

 tools/testing/selftests/hid/Makefile                | 10 ++++------
 tools/testing/selftests/hid/progs/hid.c             |  3 ---
 tools/testing/selftests/hid/progs/hid_bpf_helpers.h | 20 ++++++++++++++++++++
 3 files changed, 24 insertions(+), 9 deletions(-)
---
base-commit: 1d7546042f8fdc4bc39ab91ec966203e2d64f8bd
change-id: 20230825-wip-selftests-9a7502b56542

Best regards,
-- 
Benjamin Tissoires [off-list ref]