Blender can be started headless. In that case GHOST will use
GHOST_SystemHeadless. This system only supported OpenGL. This change
will add support for Vulkan. For users this allows to render using
Vulkan without the need of X11 or Wayland.
This should fix the cause why Vulkan tests are crashing on build-bot. They
will not work reliable due to a threading issue which is still in investigation.
Pull Request: https://projects.blender.org/blender/blender/pulls/131682
398851024a