selftests/bpf: Add some negative tests

Add a few negative tests for common mistakes with using percpu kptr
including:
  - store to percpu kptr.
  - type mistach in bpf_kptr_xchg arguments.
  - sleepable prog with untrusted arg for bpf_this_cpu_ptr().
  - bpf_percpu_obj_new && bpf_obj_drop, and bpf_obj_new && bpf_percpu_obj_drop
  - struct with ptr for bpf_percpu_obj_new
  - struct with special field (e.g., bpf_spin_lock) for bpf_percpu_obj_new

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230827152832.2002421-1-yonghong.song@linux.dev


Signed-off-by: Alexei Starovoitov <ast@kernel.org>