Fix GN formatting presubmit on Windows.

BUG=skia:

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=3182

Change-Id: I6e19b18d6851516357f71930e406b9fb324ea81f
Reviewed-on: https://skia-review.googlesource.com/3182
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Mike Klein <mtklein@chromium.org>
Reviewed-by: Herb Derby <herb@google.com>
1 file changed