Make `python build/vs_toolchain.py update` mostly work on non-Windows.

Make `python build/vs_toolchain.py update` mostly work on non-Windows.

1. GetFileList() returns a list of path\names on Windows but of path/names on
   non-Windows. To not perturb existing hashes, I guess the hashing code should do
   path.replace('/', '\\') before hashing.

2. GetFileList() returns a sorted list of filenames, and \ compares pretty
   different than / (the former is less than all numbers while the latter
   is greater, for example).  So replace / with \\ for sorting too.

With this change, OS X produces the same file hash as Windows.

The script still early-exits on non-Windows, so no visible change yet.

BUG=495204
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=296271

[Nico, 2015-08-11 20:08:35]

thakis@chromium.org changed reviewers:
+ scottmg@chromium.org

[Nico, 2015-08-11 20:08:36]

Have more mail!

[scottmg, 2015-08-11 20:09:38]

lgtm

[Nico, 2015-08-11 20:13:24]

The CQ bit was checked by thakis@chromium.org

[Nico, 2015-08-11 20:13:35]

The CQ bit was unchecked by thakis@chromium.org

[Nico, 2015-08-11 20:14:08]

The CQ bit was checked by thakis@chromium.org

[Nico, 2015-08-11 20:14:13]

The CQ bit was unchecked by thakis@chromium.org

[Nico, 2015-08-11 20:14:21]

The CQ bit was checked by thakis@chromium.org

[commit-bot: I haz the power, 2015-08-11 20:14:30]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1287543005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1287543005/1

[commit-bot: I haz the power, 2015-08-11 20:16:21]

Committed patchset #1 (id:1) as
http://src.chromium.org/viewvc/chrome?view=rev&revision=296271