bug 14857: Adding extensibility to VkSubmitInfo (WIP)

https://cvs.khronos.org/bugzilla/show_bug.cgi?id=14857
diff --git a/demos/cube.c b/demos/cube.c
index d5fa775..3a233fa 100644
--- a/demos/cube.c
+++ b/demos/cube.c
@@ -440,6 +440,8 @@
     const VkCmdBuffer cmd_bufs[] = { demo->cmd };
     VkFence nullFence = VK_NULL_HANDLE;
     VkSubmitInfo submit_info = {
+        .sType = VK_STRUCTURE_TYPE_SUBMIT_INFO,
+        .pNext = NULL,
         .waitSemCount = 0,
         .pWaitSemaphores = NULL,
         .cmdBufferCount = 1,
@@ -672,6 +674,8 @@
 
 // FIXME/TODO: DEAL WITH VK_IMAGE_LAYOUT_PRESENT_SOURCE_KHR
     VkSubmitInfo submit_info = {
+        .sType = VK_STRUCTURE_TYPE_SUBMIT_INFO,
+        .pNext = NULL,
         .waitSemCount = 1,
         .pWaitSemaphores = &presentCompleteSemaphore,
         .cmdBufferCount = 1,