pub type PFN_vkGetPhysicalDeviceExternalImageFormatPropertiesNV = unsafe extern "system" fn(_physical_device: PhysicalDevice, _format: Format, _type_: ImageType, _tiling: ImageTiling, _usage: ImageUsageFlags, _flags: ImageCreateFlags, _external_handle_type: ExternalMemoryHandleTypeFlagsNV, _external_image_format_properties: *mut ExternalImageFormatPropertiesNV) -> Result;