WSI: Small code changes to deal with latest WSI header.

A structure's sType was missed in the grand renaming that took place a while
ago, and was fixed with the latest WSI header changes.
diff --git a/demos/cube.c b/demos/cube.c
index 6507438..9fc554f 100644
--- a/demos/cube.c
+++ b/demos/cube.c
@@ -727,7 +727,7 @@
     }
 
     const VkSwapchainCreateInfoKHR swap_chain = {
-        .sType = VK_STRUCTURE_TYPE_SWAP_CHAIN_CREATE_INFO_KHR,
+        .sType = VK_STRUCTURE_TYPE_SWAPCHAIN_CREATE_INFO_KHR,
         .pNext = NULL,
         .pSurfaceDescription = (const VkSurfaceDescriptionKHR *)&demo->surface_description,
         .minImageCount = desiredNumberOfSwapchainImages,