Vulkan: Add missing layout for VK_IMAGE_LAYOUT_UNDEFINED This this was missed because it doesn't add its own enum value and instead reuses GL_NONE. Bug: chromium:976374 Test: chrome --enable-features=UseSkiaRenderer,UiGpuRasterization \ --enable-gpu-rasterization \ --enable-oop-rasterization \ --use-vulkan=native \ --use-gl=angle \ --use-angle=vulkan Change-Id: I73437211fef3253801e899cb6e50a8e18865cc65 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1665329 Commit-Queue: Michael Spang <spang@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>