vulkan: Add EXT_acquire_xlib_display [v5]

vulkan: Add EXT_acquire_xlib_display [v5]

This extension adds the ability to borrow an X RandR output for
temporary use directly by a Vulkan application. For DRM, we use the
Linux resource leasing mechanism.

v2:
	Clean up xlib_lease detection

	* Use separate temporary '_xlib_lease' variable to hold the
	  option value to avoid changin the type of a variable.

	* Use boolean expressions instead of additional if statements
	  to compute resulting with_xlib_lease value.

	* Simplify addition of VK_USE_PLATFORM_XLIB_XRANDR_KHR to
          vulkan_wsi_args

	  Suggested-by: Eric Engestrom <eric.engestrom@imgtec.com>
	Move mode list from wsi_display to wsi_display_connector

	Fix scope for wsi_display_mode and wsi_display_connector allocs

	  Suggested-by: Jason Ekstrand <jason@jlekstrand.net>
v3:
	Adopt Jason Ekstrand's coding conventions

	Declare variables at first use, eliminate extra whitespace
	between types and names. Wrap lines to 80 columns.

	Explicitly forbid multiple DRM leases. Making the code support
	this looks tricky and will require additional thought.

	Use xcb_randr_output_t throughout the internals of the
	implementation. Convert at the public API
	(wsi_get_randr_output_display).

	Clean up check for usable active_crtc (possible when only the
	desired output is connected to the crtc).

	Suggested-by: Jason Ekstrand <jason.ekstrand@intel.com>
v4:
	Move output resource fetching closer to use in
	wsi_display_get_output. This simplifies the error returns in
	earlier parts of the code a bit.

	Return VK_ERROR_INITIALIZATION_FAILED from
	wsi_acquire_xlib_display. Jason says this is the right error
	message.

	Suggested-by: Jason Ekstrand <jason.ekstrand@intel.com>
v5:
	randr doesn't pass vscan over the wire, so we set vscan to 0
	for randr-acquired modes, and test wsi modes for vscan <= 1
	when comparing against randr modes.

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