login_manager: Sorted headers alphabetically (build/include_alpha)

We are going to enable build/include_alpha linter warning soon,
so in preparation for this, fixed the warnings in login_manager.

Also fixed a few other linter issues (and a couple false-positives).

BUG=None
TEST=FEATURES=test emerge-link chromeos-login
TEST=cpplint.py --filter=-build/include_order,+build/include_alpha login_manager/*

Change-Id: I1e9d0af3e9a8e84723983ec30ca9e8425a68b7e7
Reviewed-on: https://chromium-review.googlesource.com/209822
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
Reviewed-by: Chris Masone <cmasone@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>
18 files changed