message: memory: fix memory_unused to include ptr2int
diff: @@ -471,7 +471,8 @@ static unsigned last_nonlocal_bid = 1;
  static bool memory_unused() {
  // +1 for the null block
  - return num_locals == 0 && num_nonlocals == 1 && !nullptr_is_used;
  + return num_locals == 0 && num_nonlocals == 1 && !nullptr_is_used &&
  + !observes_addresses();
  }
  Memory::Memory(State &state)
  