message: Don't add a superfluous 0x prefix in error message
  The %p includes an 0x.
diff: @@ -186,7 +186,7 @@ port::StatusOr<Platform*> MultiPlatformManagerImpl::LookupByIdLocked(
  if (it == id_map_.end()) {
  return port::Status(
  port::error::NOT_FOUND,
  - port::Printf("could not find registered platform with id: 0x%p", id));
  + port::Printf("could not find registered platform with id: %p", id));
  }
  return it->second;
  }
  