demos: Fix Windows build warnrings
demos: Fix Windows build warnrings

Change-Id: I733704e8904a77aa9071565cfc1d18b23b1c0c1c

KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers