Add speed log to examples/run_squad.py
Author: WilliamTambellini
Pull request: yes

Add a speed estimate log (time per example)
for evaluation to examples/run_squad.py

Comments:
# [Codecov](https://codecov.io/gh/huggingface/transformers/pull/1553?src=pr&el=h1) Report
> Merging [#1553](https://codecov.io/gh/huggingface/transformers/pull/1553?src=pr&el=desc) into [master](https://codecov.io/gh/huggingface/transformers/commit/fd97761c5a977fd22df789d2851cf57c7c9c0930?src=pr&el=desc) will **increase** coverage by `1.42%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/huggingface/transformers/pull/1553/graphs/tree.svg?width=650&token=9qOlN6Hb1c&height=150&src=pr)](https://codecov.io/gh/huggingface/transformers/pull/1553?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master    #1553      +/-   ##
==========================================
+ Coverage   84.74%   86.16%   +1.42%     
==========================================
  Files          91       91              
  Lines       13593    13593              
==========================================
+ Hits        11519    11713     +194     
+ Misses       2074     1880     -194
```


| [Impacted Files](https://codecov.io/gh/huggingface/transformers/pull/1553?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [transformers/modeling\_openai.py](https://codecov.io/gh/huggingface/transformers/pull/1553/diff?src=pr&el=tree#diff-dHJhbnNmb3JtZXJzL21vZGVsaW5nX29wZW5haS5weQ==) | `81.75% <0%> (+1.35%)` | :arrow_up: |
| [transformers/modeling\_ctrl.py](https://codecov.io/gh/huggingface/transformers/pull/1553/diff?src=pr&el=tree#diff-dHJhbnNmb3JtZXJzL21vZGVsaW5nX2N0cmwucHk=) | `95.45% <0%> (+2.27%)` | :arrow_up: |
| [transformers/modeling\_xlnet.py](https://codecov.io/gh/huggingface/transformers/pull/1553/diff?src=pr&el=tree#diff-dHJhbnNmb3JtZXJzL21vZGVsaW5nX3hsbmV0LnB5) | `73.28% <0%> (+2.46%)` | :arrow_up: |
| [transformers/modeling\_roberta.py](https://codecov.io/gh/huggingface/transformers/pull/1553/diff?src=pr&el=tree#diff-dHJhbnNmb3JtZXJzL21vZGVsaW5nX3JvYmVydGEucHk=) | `80.57% <0%> (+15.1%)` | :arrow_up: |
| [transformers/tests/modeling\_tf\_common\_test.py](https://codecov.io/gh/huggingface/transformers/pull/1553/diff?src=pr&el=tree#diff-dHJhbnNmb3JtZXJzL3Rlc3RzL21vZGVsaW5nX3RmX2NvbW1vbl90ZXN0LnB5) | `96.8% <0%> (+17.02%)` | :arrow_up: |
| [transformers/modeling\_tf\_pytorch\_utils.py](https://codecov.io/gh/huggingface/transformers/pull/1553/diff?src=pr&el=tree#diff-dHJhbnNmb3JtZXJzL21vZGVsaW5nX3RmX3B5dG9yY2hfdXRpbHMucHk=) | `92.95% <0%> (+83.09%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/huggingface/transformers/pull/1553?src=pr&el=continue).
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> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/huggingface/transformers/pull/1553?src=pr&el=footer). Last update [fd97761...0919389](https://codecov.io/gh/huggingface/transformers/pull/1553?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).


up ?

Why not, indeed. Ok to merge it.