int vk_submit(VkQueue q, VkCommandBuffer cmdbuf, VkSemaphore semwait, VkSemaphore semsig);
int vk_present(VkQueue q, int imgid, VkSemaphore semwait);
int vk_submit(VkQueue q, VkCommandBuffer cmdbuf, VkSemaphore semwait, VkSemaphore semsig);
int vk_present(VkQueue q, int imgid, VkSemaphore semwait);