vulkan/wsi: Add a thread-safe queue implementation

vulkan/wsi: Add a thread-safe queue implementation

In order to support FIFO mode without blocking the application on calls
to vkQueuePresentKHR it is necessary to enqueue the request and defer
calling the server until the next vblank period. The xcb present api
doesn't offer a way to register a callback, so we will have to spawn a
worker thread that will wait for a request to be added to the queue, call
to the server, and then make the image available for reuse.  This commit
introduces the queue data structure needed to implement this.

Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Cc: "13.0" <mesa-stable@lists.freedesktop.org>