Fix Linux build. We were missing several header includes necessary for GCC. Also our static assert macro had a bug, preventing us from using the same assert in multiple places. BUG=angle:568 Change-Id: I01bcdef033a9380f436cbf4bd2a9f11b1553887c Reviewed-on: https://chromium-review.googlesource.com/195471 Reviewed-by: Shannon Woods <shannonwoods@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org> Tested-by: Jamie Madill <jmadill@chromium.org>