pylint: upgrade to 1.6 (and pull in its new deps)

While cros lint should only use pylint from depot_tools, we still
want to keep these versions in sync in case devs run things by hand.

TEST=CQ passes

Change-Id: Ie2f4f2bc78f195891698acbe353f7ddb196165a8
Tested-by: Mike Frysinger <>
Commit-Ready: Mike Frysinger <>
Legacy-Commit-Queue: Commit Bot <>
Reviewed-by: Chris McDonald <>
17 files changed