Checking clang-format for C++ side

[ShahriarRezghi]

This is a PR adding clang-format check to C++ code.

[codecov-io]

Codecov Report

Merging #1274 into master will decrease coverage by 0.38%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1274      +/-   ##
==========================================
- Coverage   65.52%   65.14%   -0.39%     
==========================================
  Files          74       74              
  Lines        5784     5784              
  Branches      884      786      -98     
==========================================
- Hits         3790     3768      -22     
- Misses       1727     1742      +15     
- Partials      267      274       +7

Impacted Files	Coverage Δ
torchvision/datasets/cifar.py	71.26% <0%> (-6.9%)	⬇️
torchvision/datasets/folder.py	79.48% <0%> (-2.57%)	⬇️
torchvision/datasets/voc.py	20.87% <0%> (-2.2%)	⬇️
torchvision/datasets/lsun.py	20.83% <0%> (-2.09%)	⬇️
torchvision/datasets/utils.py	59.35% <0%> (-1.3%)	⬇️
torchvision/transforms/transforms.py	79.96% <0%> (-0.99%)	⬇️
torchvision/transforms/functional.py	69.36% <0%> (-0.87%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update c6e41b5...1feb45e. Read the comment docs.

[ShahriarRezghi]

@fmassa I think that the PR is ready. But there are errors in the format of some files:

$ ./travis-scripts/run-clang-format/run-clang-format.py -r torchvision/csrc
--- torchvision/csrc/vision.h	(original)
+++ torchvision/csrc/vision.h	(reformatted)
@@ -3,4 +3,4 @@
 
 #include <torchvision/models/models.h>

-#endif  // VISION_H
+#endif // VISION_H
--- torchvision/csrc/models/densenet.cpp	(original)
+++ torchvision/csrc/models/densenet.cpp	(reformatted)
@@ -76,8 +76,9 @@
         torch::nn::Conv2d(Options(num_input_features, num_output_features, 1)
                               .stride(1)
                               .with_bias(false)));
-    push_back(
-        "pool", torch::nn::Functional([](torch::Tensor input) { return torch::avg_pool2d(input, 2, 2, 0, false, true); }));
+    push_back("pool", torch::nn::Functional([](torch::Tensor input) {
+                return torch::avg_pool2d(input, 2, 2, 0, false, true);
+              }));
   }

   torch::Tensor forward(torch::Tensor x) {
The command "./travis-scripts/run-clang-format/run-clang-format.py -r torchvision/csrc" exited with 1.

Should I fix these here or in another PR?

[fmassa]

Thanks a lot for the PR @ShahriarSS ! Can you send a separate PR with this fix? I think the failing CI should be fine, given that this is a separate build instance.