[vulkan] Update curFrame at end of render job

This fixes the insta-death of particles. Interestingly, other than
particles (due to the ring of buffers not being used correctly),
everything else worked nicely, so I guess 1-frame rendering got tested.

libs/video/renderer/vulkan/render.c

@@ -276,6 +276,10 @@ QFV_RunRenderJob (vulkan_ctx_t *ctx)
 		0
 	};
 	dfunc->vkQueuePresentKHR (queue->queue, &presentInfo);
+
+	if (++ctx->curFrame >= rctx->frames.size) {
+		ctx->curFrame = 0;
+	}
 }
 
 static VkImageView __attribute__((pure))