tools: need to upgrade tools/cpp_lint.py to be Python 3 compatible

[cclauss]

Similar to #7462 but for Python 3 compatibility @bnoordhuis @thefourtheye

Upstream could be either:

• https://raw.githubusercontent.com/google/styleguide/gh-pages/cpplint/cpplint.py --or--
• https://github.com/cpplint/cpplint

Discovered via #25759 --> https://travis-ci.com/nodejs/node/jobs/173399622#L498

Running C++ linter on addon docs...
Traceback (most recent call last):
  File "tools/cpplint.py", line 6526, in <module>
    main()
  File "tools/cpplint.py", line 6510, in main
    ProcessFile(filename.decode('utf-8'), _cpplint_state.verbose_level)
AttributeError: 'str' object has no attribute 'decode'

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[thefourtheye]

We have diverged a little bit from the upstream, I believe. I am not sure if it would be okay to float a patch to fix this. @addaleax @bnoordhuis What do you think?

[cclauss]

@refack

[refack]

Our history (fee4d3a) indicates that our best upstream is https://github.com/cpplint/cpplint/blob/master/cpplint.py, which is was made to be python3 compatible.
PR on it's way.