Created by: heavengate
fix load_op_lib not support loading multi libs OpInfoMap is implemented in singleton mode, multi dso will use the same OpInfoMap, this may incur duplicate registration when loading latter dso, skip info_map processing if an Op is already regitered here.
OpInfoMap defined at https://github.com/PaddlePaddle/Paddle/blob/0aab2578f2479a559a1b08a031346b10a5a5a0b8/paddle/fluid/framework/op_info.cc#L27