[pyper] out variant of sigrid_transforms_torch_bind + ListUnpack (#54761)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/54761
Test Plan:
Regen adindexer model that uses sigrid_transforms_torch_bind: /mnt/public/ansha/adindexer/merge20210323/adindexer_pt_traced_merge.pt
```
MKL_NUM_THREADS=1 OMP_NUM_THREADS=1 numactl -m 0 -C 3 ./buck-out/opt/gen/caffe2/caffe2/fb/predictor/ptvsc2_predictor_bench --scripted_model=adindexer_pt_traced_merge.pt --pt_inputs=/data/users/ansha/tmp/adindexer/merge2/container_precomputation_bs1.pt --iters=30000 --warmup_iters=300000 --num_threads=1 --pred_net=c2_net_merge.pb --pt_enable_static_runtime=1 --pt_cleanup_activations=true --pt_enable_out_variant=1 --pt_optimize_memory=1
```
Before ms/iter: 0.0647056
After ms/iter: 0.0581197
Reviewed By: hlu1
Differential Revision: D27239617
fbshipit-source-id: dffe6cbaf3a783c41605c97c5947a36e3b1b1f3b
