MAIN: Update c,c++ line length to 88

[charris]

This makes the c/c++ line length the same as the modern Python defaults. Note that linux has dropped the hard 80 character limit, it is now only preferred. I don't know how to configure a linter for "preferred", so just make the hard limit 88.

[r-devulap]

Do we want to run this on the repository to reformat the existing code base?

[mattip]

I think reformatting all the code would create too much noise for the benefit gained. But if there are particular areas of the code that could be helped, we should reformat them selectively.

[mattip]

Thanks @charris