How to specify a TPU IP for run_tf_glue.py?
Hi team!

I have a VM on Google Cloud and a TPU. When running your example script `run_tf_glue.py` there is no option for specifying a TPU IP. It seems like the TPU cannot be auto-discovered and then training falls back to training on CPU 🐢 
TPUs can be autodiscovered if you use them through AI-platform by running the trainer with `gcloud ai-platform jobs submit training ...` This is the advised usage of TPUs I put in the trainer.

Nevertheless if your want to use it through its name, this is done in the following PR #4270 thanks to @ViktorAlm<|||||>This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.
