“f1143f0cdbab985d1d3878ff27a47409d237e932”上不存在“paddle/phi/kernels/gpu/unsqueeze_grad_kernel.cu”
* Fix bug in MergeModel.cpp. * Add a c-api inferface to initilize the thread environment of Paddle and add a GPU example. * Add some note for paddle_init_thread and move the inplementation of paddle_error_string into a .cpp file. * Add some comments.