Fix torchaudio build when TORCH_CUDA_ARCH_LIST is not set (pytorch#161084)

Fixes pytorch#160988.  The root cause can be found in the same issue.  This fix ensures that when reuse old wheel is on and `torchaudio` wheel is not there, the inductor test job can still rebuild the wheel it needs
Pull Request resolved: pytorch#161084
Approved by: https://github.com/malfet, https://github.com/zou3519

Author: huydhn

.ci/pytorch/common_utils.sh

@@ -152,6 +152,12 @@ function get_pinned_commit() {
 function install_torchaudio() {
   local commit
   commit=$(get_pinned_commit audio)
+  # TODO (huydhn): PyTorch CI docker image set the default TORCH_CUDA_ARCH_LIST
+  # to Maxwell. This default doesn't make sense anymore and should be cleaned up
+  if [[ "${BUILD_ENVIRONMENT}" == *cuda* ]]; then
+    TORCH_CUDA_ARCH_LIST=$(nvidia-smi --query-gpu=compute_cap --format=csv | tail -n 1)
+    export TORCH_CUDA_ARCH_LIST
+  fi
   pip_build_and_install "git+https://github.com/pytorch/audio.git@${commit}" dist/audio
 }