Export feature length information for onnxifi operator (#21303)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/21303
Export feature length information for onnxifi operator
recommit for D15548138
disable caffe2_extract_feature_length_for_shape_inference by default
change LOG(INFO) to VLOG(4)
change LOG(WARNING) to LOG_EVERY_N(WARNING, 1000)
Reviewed By: yinghai, ipiszy
Differential Revision: D15608620
fbshipit-source-id: f96410366fe6bae954fea9d6b50ee72f4969d024
