anv: Add EXT_acquire_xlib_display to anv driver [v3]

anv: Add EXT_acquire_xlib_display to anv driver [v3]

This extension adds the ability to borrow an X RandR output for
temporary use directly by a Vulkan application to the anv driver.

v2:
	Simplify addition of VK_USE_PLATFORM_XLIB_XRANDR_KHR to
	vulkan_wsi_args

	Suggested-by: Eric Engestrom <eric.engestrom@imgtec.com>
v3:
	Add extension to list in alphabetical order

	Suggested-by:  Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>