Enable calling caffe2 LayerNorm from PyTorch and JIT (#15243)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15243
Register it as a custom JIT op.
Reviewed By: dzhulgakov
Differential Revision: D13473791
fbshipit-source-id: 0f7e72e3efc85a75060a7597fadaf0a8bd289651
