turn on extended Clang warnings on Windows too

Plus some small rearrangements of the various warning lists.

Change-Id: Ied58f940341d69ddab971a529fd01b1e96b65641
Reviewed-on: https://skia-review.googlesource.com/67720
Commit-Queue: Chris Dalton <csmartdalton@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Mike Klein <mtklein@chromium.org>
20 files changed