Merge pull request #403 from pytorch/cppext-fix

fix c++ extensions tutorial

Author: soumith

advanced_source/cpp_extension.rst

@@ -428,7 +428,7 @@ class citizens of PyTorch::
       def forward(ctx, input, weights, bias, old_h, old_cell):
           outputs = lltm.forward(input, weights, bias, old_h, old_cell)
           new_h, new_cell = outputs[:2]
-          variables = outputs[1:] + [weights, old_cell]
+          variables = outputs[1:] + [weights]
           ctx.save_for_backward(*variables)
 
           return new_h, new_cell
@@ -437,7 +437,7 @@ class citizens of PyTorch::
       def backward(ctx, grad_h, grad_cell):
           outputs = lltm.backward(
               grad_h.contiguous(), grad_cell.contiguous(), *ctx.saved_variables)
-          d_old_h, d_input, d_weights, d_bias, d_old_cell, d_gates = outputs
+          d_old_h, d_input, d_weights, d_bias, d_old_cell = outputs
           return d_input, d_weights, d_bias, d_old_h, d_old_cell