fix unsorted eval_at (#2206)
fix unsorted eval_at (#2206)

* fix unsorted eval_at

* Update config.cpp

henry0312/LightGBM,henry0312/LightGBM,microsoft/LightGBM,microsoft/LightGBM,microsoft/LightGBM,microsoft/LightGBM,henry0312/LightGBM,henry0312/LightGBM,microsoft/LightGBM,henry0312/LightGBM