The changes include:
- root flag now can process non-subdirectories
-- https://github.com/google/styleguide/commit/e7ddd2af622475b0c5e0f587d69fb061d2c10c46

- root flag can be configured with CPPLINT.cfg
-- https://github.com/google/styleguide/commit/2322e4ffaa19f4c55e5679102318ce67454fb7ed

- root setting is relative to the CPPLINT.cfg file
-- https://github.com/google/styleguide/commit/8a87a46cc7f8d6cca5c0203ddba5d81149db7695

- Cleans up header file detection for hpp and hxx

- Adds quite mode

Bug: 852898

Change-Id: Id44bbfadc913cc27192049ab9a222f22d0deab5d
Reviewed-on: https://chromium-review.googlesource.com/1108381
Commit-Queue: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Aaron Gable <agable@chromium.org>