[LITE][OPENCL] Fix Places of CXX Config for OpenCL. test=develop (#3462)

* Fix Places of CXX Config for OpenCL. test=develop

* fix shared ptr as unqiue ptr. test=develop

lite/api/cxx_api.cc

@@ -293,6 +293,7 @@ void Predictor::Build(const cpp::ProgramDesc &desc,
   // `inner_places` is used to optimize passes
   std::vector<Place> inner_places = valid_places;
   for (auto &valid_place : valid_places) {
+    if (valid_place.target == TARGET(kOpenCL)) continue;
     inner_places.emplace_back(
         Place(TARGET(kHost), valid_place.precision, valid_place.layout));
   }

lite/kernels/opencl/slice_image_compute_test.cc

@@ -84,7 +84,7 @@ TEST(slice_image2d_fp16, compute) {
   }
 
   LOG(INFO) << "prepare input";
-  std::shared_ptr<CLImageConverterDefault> default_converter(
+  std::unique_ptr<CLImageConverterDefault> default_converter(
       new CLImageConverterDefault());
   DDim image_shape = default_converter->InitImageDimInfoWith(in_dim);
   LOG(INFO) << "image_shape = " << image_shape[0] << " " << image_shape[1];