The newline is probably here to protect against a hook that doesn't print
a trailing newline.  I've never seen a hook that did that, and if we found one,
we could make the logic look like "print a trailing newline if it's not there"
-- or just fix the hook.

The newline has been around since depot_tools was created
(https://codereview.chromium.org/92087, gclient.py), back then this was in
a general "run stuff" function, not in hooks-specific code.  Maybe it made
more sense back then.

This is part of a few changes to make `gclient runhooks` less noisy.

Bug: 772741
Change-Id: I285f76dc3f01c5acf5bbaa0be4db9f6edb9c0366
Reviewed-on: https://chromium-review.googlesource.com/706914Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>