Skip the bpf native tests on old devices

For older devices that doesn't have bpf support, skip the bpf native
tests so we don't get false alarms. Fixed some compiler warning and
added the clang-format check.

Test: ./libnetdbpf_test/libnetdbpf_test
Bug: 119526856
Change-Id: Icb73a8ee9b9dff9a0da28b96578e1245f1f3724f
3 files changed