selftests/bpf: Add UAF tests for arena atomics

Check that __sync_*() functions don't cause kernel panics when handling
freed arena pages.

x86_64 does not support some arena atomics yet, and aarch64 may or may
not support them, based on the availability of LSE atomics at run time.
Do not enable this test for these architectures for simplicity.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20240701234304.14336-12-iii@linux.ibm.com