frontbuffer enhancements to ANDROID_vulkan_native_buffer

Since VK_KHR_swapchain is implemented entirely in libvulkan, we need an
image-level mechanism to inform the driver that a swapchain image will
be used for front-buffered rendering. This is implemented by chaining
another structure off of the VkImageCreateInfo passed to the driver when
creating swapchain images.

V2: Don't foul up api file. Rerun code generators.
V3: Rename VkNativeBuffer2ANDROID structure to
VkSwapchainImageCreateInfoANDROID
V4: Provide nulldrv stub for new function
V5: rebase.

Change-Id: I4447400cb1782440638e4c8816b081dd8923ddb9
Test: compile
diff --git a/vulkan/libvulkan/driver_gen.h b/vulkan/libvulkan/driver_gen.h
index a60b2fe..0228ef2 100644
--- a/vulkan/libvulkan/driver_gen.h
+++ b/vulkan/libvulkan/driver_gen.h
@@ -74,6 +74,7 @@
     PFN_vkDestroyImage DestroyImage;
     PFN_vkAllocateCommandBuffers AllocateCommandBuffers;
     PFN_vkGetSwapchainGrallocUsageANDROID GetSwapchainGrallocUsageANDROID;
+    PFN_vkGetSwapchainGrallocUsage2ANDROID GetSwapchainGrallocUsage2ANDROID;
     PFN_vkAcquireImageANDROID AcquireImageANDROID;
     PFN_vkQueueSignalReleaseImageANDROID QueueSignalReleaseImageANDROID;
     // clang-format on