Vulkan: Don't request surface extensions without VK_KHR_surface ... on headless platforms. Bug: angleproject:8467 Change-Id: Id0032ddd9f57540719d90f58b7d99cfb79f91a8c Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5142626 Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Charlie Lao <cclao@google.com>