Remove forced windows version macros. These macros were causing conflicts when chrome redefines them and since we don't rely on any specific windows versions, we can remove them. BUG=angle:568 Change-Id: Ie6bf31d03cea07bf2a71ffa6d815dad2b4d204f8 Reviewed-on: https://chromium-review.googlesource.com/195364 Reviewed-by: Shannon Woods <shannonwoods@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Tested-by: Geoff Lang <geofflang@chromium.org>