checkpatch.pl: Update to latest from v4.11

Copied checkpatch and related files from the v4.11 kernel.org
repository.

BUG=b:63422948
TEST=try to upload some good and bad patches (including missing sign-off)
with `repo upload` and verified expected behavior

Change-Id: I853605febf248f2357c88aca978a5a6c7752f64d
Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/563498
Commit-Ready: Shawn N <shawnn@chromium.org>
Tested-by: Shawn N <shawnn@chromium.org>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
3 files changed