Fix logging in the examples
# What does this PR do?

This PR updates all the examples to use the Transformers logging util. Before no logs was displayed.
The five examples scripts mentioned above all already use the huggingface logger, and already set it to the correct verbosity level. Seeing as the example scripts are *examples*, they really should be as straightforward as possible, and should not repeat unnecessary statements.

Please update the following files: `run_clm.py`, `run_mlm.py`, `run_glue.py`, `run_mlm_wwm.py`, `run_plm.py` so that they do not have useless statements.

@sgugger pointed you towards the correct area, you should be able to find it if you look for "logging".<|||||>I don't see the import neither the usage. Can you link it please?<|||||>https://github.com/huggingface/transformers/blob/master/examples/language-modeling/run_clm.py#L170<|||||>Ok got it I was looking at my own updated file ahah.<|||||>It is also in your file, below https://github.com/huggingface/transformers/blob/d410b83111238f7b949b7c9c6a4c3f689d29519b/examples/language-modeling/run_clm.py#L176<|||||>Ok I have removed the duplicate import and add only the two missing calls.<|||||>Already done the changes 👍 <|||||>No, the changes are not done:
1. in the scripts like the new `run_glue.py`, the code for logging is duplicated and executed once for every process, then once for the main process.
2. in all the other scripts, the code is executed on all processes.

This is also added in util files or test files where it's just not necessary.<|||||>I really don't get what you mean, sorry. What are the exact changes I have to make for each file?<|||||>@sgugger Please check the last commit and let me know if it was what you meant. Otherwise, please, can you be more specific in what you want me to change.