Created by: heavengate

fix use_fine_grained_loss eval in train EvalReader and build_inputs in eval mode should not set use_fined_grained_loss for no loss is calculated in eval/infer mode. Following error will be occur when use --eval in training

2020-01-06 09:20:37,224-WARNING: recv endsignal from outq with errmsg[consumer[consumer-0be-1] failed to map with error:[target0 not in samples]]

use whether im_size is in fields to distinguish train and eval/infer mode

备选方案：

• build_inputs中加入mode参数，由train/eval/infer中传入该参数区分当前mode，需要修改所有architecture
• 读取配置后，将-o use_fine_grained_loss=true设置的配置同步到TrainReader.input_def，需要在train.py中新增硬编码处理