L1Loss module (#25902)
Summary:
yf225 This is L1Loss module. I don't think that ```_Loss``` and ```_WeightedLoss``` as base Python classes do anything. First one sets reduction type and also takes in ```reduce``` parameter which is deprecated. The second one only registers ```weight``` parameter. I don't think that we should keep this structure. What do you think?
Pull Request resolved: https://github.com/pytorch/pytorch/pull/25902
Differential Revision: D17307045
Pulled By: yf225
fbshipit-source-id: ad3eda2ee8dcf4465054b376c1be89b39d11532f
