bpf, selftests: Add test cases for pointer alu from multiple paths

Add several test cases for checking update_alu_sanitation_state() under
multiple paths:

  # ./test_verifier
  [...]
  #1061/u map access: known scalar += value_ptr unknown vs const OK
  #1061/p map access: known scalar += value_ptr unknown vs const OK
  #1062/u map access: known scalar += value_ptr const vs unknown OK
  #1062/p map access: known scalar += value_ptr const vs unknown OK
  #1063/u map access: known scalar += value_ptr const vs const (ne) OK
  #1063/p map access: known scalar += value_ptr const vs const (ne) OK
  #1064/u map access: known scalar += value_ptr const vs const (eq) OK
  #1064/p map access: known scalar += value_ptr const vs const (eq) OK
  #1065/u map access: known scalar += value_ptr unknown vs unknown (eq) OK
  #1065/p map access: known scalar += value_ptr unknown vs unknown (eq) OK
  #1066/u map access: known scalar += value_ptr unknown vs unknown (lt) OK
  #1066/p map access: known scalar += value_ptr unknown vs unknown (lt) OK
  #1067/u map access: known scalar += value_ptr unknown vs unknown (gt) OK
  #1067/p map access: known scalar += value_ptr unknown vs unknown (gt) OK
  [...]
  Summary: 1762 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>