vulkan/wsi/x11: wait for acquirable images in FIFO mode

vulkan/wsi/x11: wait for acquirable images in FIFO mode

In FIFO presentation mode we block either on our present-queue or on Present
events after an image was transmitted.

In case we receive completion events without idle events at some point we
exhaust our acquire-queue and can not block anymore on present-queue.

Ensure that the consumer has at least one image to acquire before blocking
again on present-queue. Otherwise wait for one from the X server.

CC: mesa-stable
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/3344
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Reviewed-by: Simon Ser <contact@emersion.fr>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6513>