Updating clang-format to 5.0 to get a bit more control over our
styling. Two things that will be beneficial:

- Alphabeticalize headers
- More control around line breaking, especially preferring

val = SomeFunction(arg1,
                   arg2);

vs:

val =
    SomeFunction(arg1, arg2);

It's still not perfect, but it seems greatly improved.

Signed-off-by: Sean Paul <seanpaul@chromium.org>