“af64f39bfd2ba99c2bba36926c5b45c4f2015609”上不存在“paddle/phi/kernels/impl/maxout_grad_kernel_impl.h”
* 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.