Fix compile error on mac caused by std move

[jacquesqiao]

fix: #11032

it's strange why CreatePaddlePredictorImpl do not have the same problem on manylinux

Paddle/paddle/contrib/inference/paddle_inference_api_impl.cc

Lines 287 to 308 in 654f5d3

	std::unique_ptr<PaddlePredictorImpl> CreatePaddlePredictorImpl(
	const VisConfig &config) {
	VLOG(3) << "create PaddlePredictorImpl";
	// 1. GPU memeroy
	std::vector<std::string> flags;
	if (config.fraction_of_gpu_memory >= 0.0f ||
	config.fraction_of_gpu_memory <= 0.95f) {
	flags.push_back("dummpy");
	std::string flag = "--fraction_of_gpu_memory_to_use=" +
	num2str<float>(config.fraction_of_gpu_memory);
	flags.push_back(flag);
	VLOG(3) << "set flag: " << flag;
	framework::InitGflags(flags);
	}
	std::unique_ptr<PaddlePredictorImpl> predictor(
	new PaddlePredictorImpl(config));
	if (!predictor->Init()) {
	return nullptr;
	}
	return predictor;
	}

[Superjomn]

this will make mac success but make manylinux fail.

try return pointer, that mac works and might make manylinux success.

[jacquesqiao]

There are many codes in fluid return a unique_ptr without the problem. Not sure why this place face problem on manylinux build.

[Superjomn]

LGTM

[luotao1]

LGTM