Function vkGetPhysicalDeviceDirectFBPresentationSupportEXT 

pub unsafe extern "system" fn vkGetPhysicalDeviceDirectFBPresentationSupportEXT(
    physicalDevice: VkPhysicalDevice,
    queueFamilyIndex: u32,
    dfb: *mut IDirectFB,
) -> VkBool32

Available if built with prototypes.