Remove unused forward def

apex/contrib/csrc/optimizers/multi_tensor_distopt_lamb.cpp

 #include <torch/extension.h>
 
-void multi_tensor_lamb_cuda(
-  int chunk_size,
-  at::Tensor noop_flag,
-  std::vector<std::vector<at::Tensor>> tensor_lists,
-  const float lr,
-  const float beta1,
-  const float beta2,
-  const float epsilon,
-  const int step,
-  const int bias_correction,
-  const float weight_decay,
-  const int grad_averaging,
-  const int mode,
-  const float global_grad_norm,
-  const float max_grad_norm,
-  at::optional<bool> use_nvlamb_python);
-
 void multi_tensor_lamb_compute_update_term_cuda(
   int chunk_size,
   at::Tensor noop_flag,