(Vulkan) Negotiation interface v3: a presentation queue in the graphics family

A presentation_queue that is another queue of queue_family_index is only
valid for a frontend that takes one, so it gets a version of its own.
GET_HW_RENDER_CONTEXT_NEGOTIATION_INTERFACE_SUPPORT reports 3, and a core
may hand back that queue only when it sees 3 or higher. Frontends below
that fail context creation on any presentation_queue that is not the
graphics queue.

Acceptance stays version-agnostic: a core that provides the queue without
asking is still honoured when the family matches.

libretro-common/include/libretro_vulkan.h

@@ -27,7 +27,7 @@
 #include <vulkan/vulkan.h>
 
 #define RETRO_HW_RENDER_INTERFACE_VULKAN_VERSION 5
-#define RETRO_HW_RENDER_CONTEXT_NEGOTIATION_INTERFACE_VULKAN_VERSION 2
+#define RETRO_HW_RENDER_CONTEXT_NEGOTIATION_INTERFACE_VULKAN_VERSION 3
 
 struct retro_vulkan_image
 {
@@ -155,6 +155,13 @@ struct retro_hw_render_context_negotiation_interface_vulkan
     * If surface is not VK_NULL_HANDLE, the instance from frontend will have been created with supported for
     * VK_KHR_surface extension.
     *
+    * v3: presentation_queue may be another queue of queue_family_index even when presentation is supported
+    * on queue itself, which takes the frontend's present off the queue the core submits to and off its lock.
+    * presentation_queue_family_index must still equal queue_family_index; another family would need an image
+    * ownership transfer around every frame and is rejected.
+    * A core must only do this when GET_HW_RENDER_CONTEXT_NEGOTIATION_INTERFACE_SUPPORT reports 3 or higher:
+    * earlier frontends reject a presentation_queue that is not queue and fail context creation.
+    *
     * The core is free to set its own queue priorities.
     * Device provided to frontend is owned by the frontend, but any additional device resources must be freed by core
     * in destroy_device callback.