D3D11: Convert the FL 9_3 vertex format table to constexpr. This removes a static global map initialization. BUG=angleproject:1389 BUG=angleproject:1459 Change-Id: I6eb19f6649280e72682c6806ea0bf6eb70173984 Reviewed-on: https://chromium-review.googlesource.com/405487 Reviewed-by: Yuly Novikov <ynovikov@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>